[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-11-23 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Status: Open  (was: Patch Available)

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Fix For: 3.4.0

 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-11-23 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

This patch:
* Fixes the findbugs warnings
* Fixes the testSessionTimeout() failure on the SessionTest 

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Fix For: 3.4.0

 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-11-23 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Status: Patch Available  (was: Open)

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Fix For: 3.4.0

 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-11-17 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12933307#action_12933307
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Thanks for the feedback Flavio. After some investigation, I have noticed that, 
with the patch applied, the server threads take longer to be released in the 
tests. I have measured the time that the QuorumPeer.join() invocations take on 
the QuorumBase.shutdown() method, and it seems that most of the time difference 
relies on these invocations. 
However, I am still trying to find out what is causing these threads to be 
delayed. I need to investigate it further.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Fix For: 3.4.0

 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-11-02 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

Hi Flavio, Thanks for the comments. In this patch I have removed the normal 
distribution option for the PhiAccrual, and also the math-commons dependency in 
the ivy.xml file. With this modification, the PhiTimeoutEvaluator (and its 
implementations) are no longer needed.

I also have refactored some of the common code regarding the ping sampling 
window. This made the code of the adaptive FDs clearer.

Regarding my last experiments, I will post the results on the wiki asap.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Fix For: 3.4.0

 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-11-02 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

* Updated with trunk.
* Fixed the standard deviation calculus in the InterArrivalSamplingWindow.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Fix For: 3.4.0

 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-10-19 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

After making some more experiments with the Phi Accrual, I have noticed that 
the exponential distribution fits the ping inter-arrival sampling window 
better. 
Then, I have added a new option for the PhiAccrual called 'dist', that is the 
distribution used to model the inter-arrivals. 
Two possible values for this parameter are 'norm' and 'exp', and the default is 
'exp'. When we set the PhiAccrual to use the exponential distribution, it will 
work similar to the Cassandra's failure detector.


 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-10-19 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Status: Patch Available  (was: Open)

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-09-28 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Status: Patch Available  (was: Open)

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-09-28 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

Fixed the issue on the patch generation that Flavio mentioned.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-09-26 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

Thanks for the feedback Flavio, I have fixed the issue you mentioned. Only the 
new quorum hammer tests were not working propertly, they were creating the 
default failure detector in all the test cases. This patch addresses this issue.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-09-21 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

In this patch:
* Replaced 'heartbeat' for 'ping' in the forrest documentation
* Revised javadocs
* Expanded the hammer (client and quorum) and recovery tests to exercise all 
failure detectors implementations.

Flavio, I have run the tests you mentioned and they seem to fail in the trunk 
also.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-09-13 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

In this patch:
* Added support for declaring new failure detectors, as Ivan suggested.
* Updated documentation to reflect this.
* Replaced all 'heartbeat' mentions in the API and tests for 'ping'.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-09-13 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12908876#action_12908876
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Hi Ivan, thanks for the feedback.

I thought the idea was to declare an alias to a custom failure detector, so 
setting its options would be more user friendly. e.g.:

sessionsFD = myfd
sessionsFD.myfd = com.softwaresoft.zk.myFailureDetector
sessionsFD.myfd.blahblah = foobar
sessionsFD.myfd.myoption = barfoo

In this case, I need both className and fdName parameters in the factory code 
(and this is how it is implemented in the patch).
What do you think?

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

-- 
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You can reply to this email to add a comment to the issue online.



[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-30 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

I this patch I have addressed all the issues Ivan and Flavio raised, but the 
reflection code on the FaiilureDetectorFactory, in which I am working.

What do you think is the most user-friendly way of configuring the failure 
detector? (using reflection on the FailureDetectorFactory). 

Should we require the fully classified class name in the fd.classname option 
and the parameters should be like fd.param1, fd.param2...? In this sense, 
should we force the failure detectors classes to have methods like 
setParam1(String param1), setParam2(String param2)...?

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-20 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12900826#action_12900826
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Hi Flavio,

As we are using inter arrival times and a flexible sampling window, it can work 
the same way of Chen's estimation in both cases (j = n or j  n).

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-492) the tests should have their own log4j.properties

2010-08-16 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12898802#action_12898802
 ] 

Abmar Barros commented on ZOOKEEPER-492:


I have just checked out the ZooKeeper trunk in Eclipse (running on Windows) and 
3/5 tests from the QuorumPeerMainTest fail due to a NullPointerException while 
recovering CONSOLE appender. Is this supposed to happen?

 the tests should have their own log4j.properties
 

 Key: ZOOKEEPER-492
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-492
 Project: Zookeeper
  Issue Type: Bug
  Components: tests
Affects Versions: 3.1.1, 3.2.0
Reporter: Patrick Hunt
Priority: Minor
 Fix For: 3.4.0


 the tests currently rely (QuorumPeerMainTest in particular) on 
 conf/log4j.properties. if the user changes this file
 and then runs the tests the tests may fail. the tests should have their own 
 log4j.properties maintained w/in the test
 directory itself, separate from conf/log4j.properties

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-16 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12899105#action_12899105
 ] 

Abmar Barros commented on ZOOKEEPER-702:


I have updated the wiki page with the results of the experiments:
http://wiki.apache.org/hadoop/ZooKeeper/GSoCFailureDetector

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Created: (ZOOKEEPER-848) Implement the Failure Detector module in the C client

2010-08-15 Thread Abmar Barros (JIRA)
Implement the Failure Detector module in the C client
-

 Key: ZOOKEEPER-848
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-848
 Project: Zookeeper
  Issue Type: Improvement
  Components: c client
Reporter: Abmar Barros


The failure detector module https://issues.apache.org/jira/browse/ZOOKEEPER-702 
is only used in the java client of ZooKeeper, once it reuses the implementation 
written in Java. The failure detectors must be written in C and the C client 
must be refactored to use them.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-15 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch
ZOOKEEPER-702-code.patch
ZOOKEEPER-702-doc.patch

In this patch:
* Fixed a delay in client heartbeat sending, that was causing unit tests to run 
slowly.
* Added a new parameter to phi accrual FD - the minimum window size to begin 
timeout adaptation.
* Added a moderation step to Bertier FD, to comply with second level task 
described in his paper.
* Made Chen's alpha parameter configurable, and not a quarter of the timeout.
* Removed ^M characters from the patch lines.

I also have splitted the patch in two parts: one containing the failure 
detector module source code (ZOOKEEPER-702-code.patch) and another containing 
the documentation (ZOOKEEPER-702-doc.patch).

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702-code.patch, ZOOKEEPER-702-doc.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-13 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12898471#action_12898471
 ] 

Abmar Barros commented on ZOOKEEPER-702:


I was thinking of adding a new parameter to the adaptive methods, that is the 
minimum window size to begin performing timeout adaptation. As we noticed, 
adaptive methods can get benefit of a large window size, and there can be 
premature false suspicion if we do not know the behaviour of the network. In 
this case, the methods will start using a static timeout until the window 
reaches a certain size. What do you think?

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-10 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

* Synchronized patch with updates from trunk
* Put all changes from subtasks together in the this patch

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-08-10 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Status: Patch Available  (was: Open)

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-29 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

In this patch I removed some tests modifications that were not intended to be 
committed.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-811) Failure Detector Model: Refactor server to server monitoring

2010-07-29 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-811?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-811:
---

Attachment: ZOOKEEPER-811.patch

In this patch:
 * Leaders use the FailureDetector interface to monitor learners.
 * Added learners failure detector options to server configuration file.

 Failure Detector Model: Refactor server to server monitoring
 

 Key: ZOOKEEPER-811
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-811
 Project: Zookeeper
  Issue Type: Sub-task
Reporter: Abmar Barros
Assignee: Abmar Barros
 Attachments: ZOOKEEPER-811.patch


 Refactor server to server failure detection code to use the FailureDetector 
 interface proposed in the parent JIRA. The failure detection method and its 
 parameters should also be configurable in this case. 
 Patches submitted in this JIRA use the latest patch of the parent JIRA as 
 baseline.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-28 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12893072#action_12893072
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Hi Benjamin

Thanks for your feedback!
Regarding your first question, a failure detector is intended to determine when 
monitored objects are to be pinged and when they are supposed to have failed. 
So, you can have two different failure detectors running in two sides of the 
application, or you can have the failure detector in just one side, and the 
other side just replies the pings messages. 
Summarizing,  a failure detector implementation is absolutely responsible for 
one side of the monitoring.

Concerning your note, the failure detectors I have implemented rely on the 
assumption that zk (TCP) guarantees massage delivery and in order.  To see the 
effects of the new failure detection methods, we are planning to do some 
experiments in the next week. We can also check if there is any effect of TCP 
in the adaptive fds behavior.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-28 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

In this patch:
 * Refactored SessionTracker and Heartbeat tracking on learners.
 * Fixed an issue concerning server recovery.

Patches of the subtasks use this patch as a baseline. 

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-19 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

In this patch: 
* Learners report clients heartbeat sample information (mean and standard 
deviation) to Leaders. 

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-16 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12889280#action_12889280
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Hi Diogo! Thank you for indicating this paper, I haven't found such failure 
detection type so far, it is very interesting. 

It proposes a simple way of estimating heartbeats arrival times based on 
application messages. However it does require the attachment of sending times 
to all application messages (or at least the ones it will use to do the 
estimation), which is an overhead to message size. Anyway, with the separate 
failure detector module, it would be easy to implement a new Failure Detector 
that uses such data.

So far, I have adapted the proposed failure detectors in order to compute the 
estimated next arrival time only when a heartbeat is received.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-14 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12888523#action_12888523
 ] 

Abmar Barros commented on ZOOKEEPER-702:


As I was refactoring server-to-server monitoring, I noticed that Leaders cannot 
process the client session heartbeats received by Learners, once they only 
track the last heartbeat (or app message) received from the clients, in order 
to report to the Leader (LearnerSessionTracker).

I am thinking of tracking the heartbeats (not app messages) received from the 
clients in the LearnerSessionTracker, so the Learners can send them to the 
Leader, and the Leader itself can do an adaptive monitoring on these clients 
too.

What do you think? 

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Created: (ZOOKEEPER-810) Failure Detector Model: Write Forrest docs

2010-07-12 Thread Abmar Barros (JIRA)
Failure Detector Model: Write Forrest docs
--

 Key: ZOOKEEPER-810
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-810
 Project: Zookeeper
  Issue Type: Sub-task
Reporter: Abmar Barros
Assignee: Abmar Barros


Write forrest docs about the Failure Detector Model implementation. 

This documentation should help one to understand how the failure detection 
model works on ZooKeeper, both on client and server sides. The usage and 
configuration of this feature should also be addressed in this documentation.

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[jira] Created: (ZOOKEEPER-811) Failure Detector Model: Refactor server to server monitoring

2010-07-12 Thread Abmar Barros (JIRA)
Failure Detector Model: Refactor server to server monitoring


 Key: ZOOKEEPER-811
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-811
 Project: Zookeeper
  Issue Type: Sub-task
Reporter: Abmar Barros
Assignee: Abmar Barros


Refactor server to server failure detection code to use the FailureDetector 
interface proposed in the parent JIRA. The failure detection method and its 
parameters should also be configurable in this case. 

Patches submitted in this JIRA use the latest patch of the parent JIRA as 
baseline.

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[jira] Created: (ZOOKEEPER-812) Failure Detector Model: Evaluate QoS metrics

2010-07-12 Thread Abmar Barros (JIRA)
Failure Detector Model: Evaluate QoS metrics


 Key: ZOOKEEPER-812
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-812
 Project: Zookeeper
  Issue Type: Sub-task
Reporter: Abmar Barros
Assignee: Abmar Barros




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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-07 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12886224#action_12886224
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Hi Flavio, actually I was talking about the client monitoring on the 
server-side (SessionTracking).

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-07 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

In this patch:

* Adapted failure detectors to work on both client and server sides of the 
client-server monitoring.
* Refactored server-side code to use the FailureDetector interface.
* Created a new FailureDetector, which groups monitoreds by their tick time, 
similar to what the SessionTracking does.
* Made the failure detector (and its parameters) options of the ZooKeeper 
configuration file.
* Corrected indentation (spaces instead of tabs).

Next steps are:
* As suggested by Flavio, create sub tasks in this Jira for:
** Experimentation.
** Refactor server-server monitoring to use FailureDetector interface and make 
it configurable.
** Forrest documentation.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
 ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-02 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: bertier-pseudo.txt
chen-pseudo.txt
phiaccrual-pseudo.txt

Added more comments to pseudo codes.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-07-02 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

Patch changes are:
* Created appMessageReceived() and appMessageSent() methods. These methods 
allow the Failure Detector to use application messages as heartbeats, which 
reflects the ZooKeeper case.
* Added command line options to configure failure detector method and its 
parameters.
* Unit tests expanded to comply with new methods.
* Enhanced javadocs for each Failure Detector implementation
* Added commons-math dependency to ivy.xml

Next things to work on are:
* Adapt server side code to use the proposed FD interface
* Start experimenting

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
 chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
 ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-06-28 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12883334#action_12883334
 ] 

Abmar Barros commented on ZOOKEEPER-702:


As discussed with Flavio, I am thinking of adding a new parameter called -fd to 
the client, which will determine the name of the failure detector to be used. 
In this sense, the parameters of the failure detector will have its name as 
prefix, for instance:

-fd chen -fd.chen.alpha 1

In the server side, these parameters are intended to be defined in the 
ZooKeeper configuration file.
What do you think?

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, chen-pseudo.txt, 
 phiaccrual-pseudo.txt, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-06-24 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12882063#action_12882063
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Sure Flavio, so it will take another step:
* Make failure detector method and parameters configurable by the user.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, chen-pseudo.txt, 
 phiaccrual-pseudo.txt, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-06-22 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: ZOOKEEPER-702.patch

Agreed with what Flavio said about the second point. The application scheduling 
interval is, indeed, much lower than the FD pinging interval.

Attached the implementations of all initially suggested FDs and their unit 
tests. Also have included the suggestions Flavio gave concerning package naming 
and method scope. 

Once the Phi Accrual implementation needs to compute the Normal Distribution 
cdf, I have used the math-commons API, however, it still has to be added as an 
Ivy dependency.

So, before experimenting, there are a few steps that need to be accomplished:

* Create a receiveAppHeartbeat() method on the interface so that we can keep 
using zookeeper messages as heartbeats and analyze its impact and adapt it to 
each FD implementation
* Adapt server side code to use the proposed FD interface
* Add comments to pseudo codes
* Expand unit tests
* Enhance code documentation
* Add math-commons dependency to Ivy

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, chen-pseudo.txt, 
 phiaccrual-pseudo.txt, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-06-16 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12879450#action_12879450
 ] 

Abmar Barros commented on ZOOKEEPER-702:


Once ZooKeeper  guarantees delivery order, I can ignore the seq field in 
heartbeat and pings messages. 
Now I am implementing the methods on the interface I proposed and two issues 
came to mind:
* ZooKeeper uses application messages as hearbeats, so actual pings and 
heartbeats are used only at idle states. The proposed methods must be adapted 
to consider this scenario.
* Regarding that a single thread is being used for the app and the FD, there is 
a delay between the time a monitored must be pinged and the time it is actually 
pinged. The impact of this delay in the FD QoS must be analyzed.



 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, chen-pseudo.txt, 
 phiaccrual-pseudo.txt, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Updated: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-06-11 Thread Abmar Barros (JIRA)

 [ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Abmar Barros updated ZOOKEEPER-702:
---

Attachment: bertier-pseudo.txt
chen-pseudo.txt
phiaccrual-pseudo.txt

Attached the pseudo-codes for the failure detectors I have proposed. It seems I 
need to include the heartbeat sequence number in the receiveHeartbeat method of 
the FailureDetector interface in order to implement some of these FDs. 

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros
 Attachments: bertier-pseudo.txt, chen-pseudo.txt, 
 phiaccrual-pseudo.txt, ZOOKEEPER-702.patch


 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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[jira] Commented: (ZOOKEEPER-702) GSoC 2010: Failure Detector Model

2010-06-01 Thread Abmar Barros (JIRA)

[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12874163#action_12874163
 ] 

Abmar Barros commented on ZOOKEEPER-702:


I have updated the wiki page for this 
(http://wiki.apache.org/hadoop/ZooKeeper/GSoCFailureDetector), including a 
discussion on whether there should be another thread for failure detection. 
I have previously discussed it with Flavio in order to raise benefits and 
drawbacks of including another thread in the application and we are expecting 
feedback to make this decision.

 GSoC 2010: Failure Detector Model
 -

 Key: ZOOKEEPER-702
 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
 Project: Zookeeper
  Issue Type: Wish
Reporter: Henry Robinson
Assignee: Abmar Barros

 Failure Detector Module
 Possible Mentor
 Henry Robinson (henry at apache dot org)
 Requirements
 Java, some distributed systems knowledge, comfort implementing distributed 
 systems protocols
 Description
 ZooKeeper servers detects the failure of other servers and clients by 
 counting the number of 'ticks' for which it doesn't get a heartbeat from 
 other machines. This is the 'timeout' method of failure detection and works 
 very well; however it is possible that it is too aggressive and not easily 
 tuned for some more unusual ZooKeeper installations (such as in a wide-area 
 network, or even in a mobile ad-hoc network).
 This project would abstract the notion of failure detection to a dedicated 
 Java module, and implement several failure detectors to compare and contrast 
 their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
 phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
 is much more tunable and has some very interesting properties. This is a 
 great project if you are interested in distributed algorithms, or want to 
 help re-factor some of ZooKeeper's internal code.

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