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https://issues.apache.org/jira/browse/HDFS-9107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14908831#comment-14908831
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Hudson commented on HDFS-9107:
------------------------------

FAILURE: Integrated in Hadoop-Mapreduce-trunk-Java8 #441 (See 
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk-Java8/441/])
HDFS-9107. Prevent NN's unrecoverable death spiral after full GC (Daryn Sharp 
via Colin P. McCabe) (cmccabe: rev 4e7c6a653f108d44589f84d78a03d92ee0e8a3c3)
* 
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/HeartbeatManager.java
* 
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestHeartbeatHandling.java
Add HDFS-9107 to CHANGES.txt (cmccabe: rev 
878504dcaacdc1bea42ad571ad5f4e537c1d7167)
* hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt


> Prevent NN's unrecoverable death spiral after full GC
> -----------------------------------------------------
>
>                 Key: HDFS-9107
>                 URL: https://issues.apache.org/jira/browse/HDFS-9107
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 2.0.0-alpha
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>             Fix For: 2.8.0
>
>         Attachments: HDFS-9107.patch, HDFS-9107.patch
>
>
> A full GC pause in the NN that exceeds the dead node interval can lead to an 
> infinite cycle of full GCs.  The most common situation that precipitates an 
> unrecoverable state is a network issue that temporarily cuts off multiple 
> racks.
> The NN wakes up and falsely starts marking nodes dead. This bloats the 
> replication queues which increases memory pressure. The replications create a 
> flurry of incremental block reports and a glut of over-replicated blocks.
> The "dead" nodes heartbeat within seconds. The NN forces a re-registration 
> which requires a full block report - more memory pressure. The NN now has to 
> invalidate all the over-replicated blocks. The extra blocks are added to 
> invalidation queues, tracked in an excess blocks map, etc - much more memory 
> pressure.
> All the memory pressure can push the NN into another full GC which repeats 
> the entire cycle.



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