[
https://issues.apache.org/jira/browse/ZOOKEEPER-885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12918940#action_12918940
]
Alexandre Hardy commented on ZOOKEEPER-885:
-------------------------------------------
{{maxClientCnxns}} is set to 30, so 45 clients spread across 3 servers should
not be unreasonable, and I do have confirmation that a session is established
for every client (all 45 of them) before beginning the disk load with {{dd}}.
I'm aiming for 0 disconnects with this simple example.
> Zookeeper drops connections under moderate IO load
> --------------------------------------------------
>
> Key: ZOOKEEPER-885
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-885
> Project: Zookeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.2.2
> Environment: Debian (Lenny)
> 1Gb RAM
> swap disabled
> 100Mb heap for zookeeper
> Reporter: Alexandre Hardy
> Priority: Critical
> Attachments: WatcherTest.java
>
>
> A zookeeper server under minimum load, with a number of clients watching
> exactly one node will fail to maintain the connection when the machine is
> subjected to moderate IO load.
> In a specific test example we had three zookeeper servers running on
> dedicated machines with 45 clients connected, watching exactly one node. The
> clients would disconnect after moderate load was added to each of the
> zookeeper servers with the command:
> {noformat}
> dd if=/dev/urandom of=/dev/mapper/nimbula-test
> {noformat}
> The {{dd}} command transferred data at a rate of about 4Mb/s.
> The same thing happens with
> {noformat}
> dd if=/dev/zero of=/dev/mapper/nimbula-test
> {noformat}
> It seems strange that such a moderate load should cause instability in the
> connection.
> Very few other processes were running, the machines were setup to test the
> connection instability we have experienced. Clients performed no other read
> or mutation operations.
> Although the documents state that minimal competing IO load should present on
> the zookeeper server, it seems reasonable that moderate IO should not cause
> problems in this case.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
