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https://issues.apache.org/jira/browse/CASSANDRA-8860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14339828#comment-14339828
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Phil Yang edited comment on CASSANDRA-8860 at 2/27/15 7:15 AM:
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I submit a patch to fix this issue.
The idea is very simple: keep only one overlapChain in heap whose
estimateCompactionGain < 0.7 and has the max size from any other overlapChains.
It is still O(N^2) time complexity and generate O(N^2) Entry objects, but
useless Entry objects will be recycled because it only keeps at most O(N) Entry
objects simultaneously.
was (Author: yangzhe1991):
I submit a patch to fix this issue.
The idea is very simple: keep only one overlapChain in heap whose
estimateCompactionGain < 0.7 and has the max size from any other overlapChains.
> Too many java.util.HashMap$Entry objects in heap
> ------------------------------------------------
>
> Key: CASSANDRA-8860
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8860
> Project: Cassandra
> Issue Type: Bug
> Environment: Cassandra 2.1.3, jdk 1.7u51
> Reporter: Phil Yang
> Assignee: Marcus Eriksson
> Fix For: 2.1.4
>
> Attachments: 8860.txt, cassandra-env.sh, cassandra.yaml, jmap.txt,
> jstack.txt
>
>
> While I upgrading my cluster to 2.1.3, I find some nodes (not all) may have
> GC issue after the node restarting successfully. Old gen grows very fast and
> most of the space can not be recycled after setting its status to normal
> immediately. The qps of both reading and writing are very low and there is no
> heavy compaction.
> Jmap result seems strange that there are too many java.util.HashMap$Entry
> objects in heap, where in my experience the "[B" is usually the No1.
> If I downgrade it to 2.1.1, this issue will not appear.
> I uploaded conf files and jstack/jmap outputs. I'll upload heap dump if
> someone need it.
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