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https://issues.apache.org/jira/browse/HADOOP-8942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13483821#comment-13483821
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Hudson commented on HADOOP-8942:
--------------------------------
Integrated in Hadoop-trunk-Commit #2925 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/2925/])
MAPREDUCE-4730. Fix Reducer's EventFetcher to scale the map-completion
requests slowly to avoid HADOOP-8942. Contributed by Jason Lowe. (Revision
1401941)
Result = SUCCESS
vinodkv :
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1401941
Files :
* /hadoop/common/trunk/hadoop-mapreduce-project/CHANGES.txt
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/EventFetcher.java
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Shuffle.java
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestEventFetcher.java
> Thundering herd of RPCs with large responses leads to OOM
> ---------------------------------------------------------
>
> Key: HADOOP-8942
> URL: https://issues.apache.org/jira/browse/HADOOP-8942
> Project: Hadoop Common
> Issue Type: Bug
> Components: ipc
> Affects Versions: 0.23.3
> Reporter: Jason Lowe
>
> When a large number of clients are all making calls with large amounts of
> response data then the IPC server can exhaust memory. See MAPREDUCE-4730 for
> an example of this.
> There does not appear to be any flow control between the server's handler
> threads and the responder thread. If a handler thread cannot write out all
> of the response data without blocking, it queues up the remainder for the
> responder thread and goes back to the next call in the call queue. If there
> are enough clients, this can cause the handler threads to overwhelm the heap
> by queueing response data faster than it can be processed.
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