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https://issues.apache.org/jira/browse/HDFS-9520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15109320#comment-15109320
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Chris Nauroth commented on HDFS-9520:
-------------------------------------
[~rajesh.balamohan], as per the prior comments from me and Colin, we cannot
make the suggested code change. Shall we resolve this as Won't Fix?
Alternatively, do you want to keep it open as a request to increase the default
cache capacity like Colin described?
> PeerCache evicts too frequently causing connection restablishments
> ------------------------------------------------------------------
>
> Key: HDFS-9520
> URL: https://issues.apache.org/jira/browse/HDFS-9520
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Rajesh Balamohan
> Attachments: HDFS-9520.png
>
>
> Env: 20 node setup
> dfs.client.socketcache.capacity = 16
> Issue:
> ======
> Monitored PeerCache and it was evicting lots of connections during close. Set
> "dfs.client.socketcache.capacity=20" and tested again. Evictions still
> happened. Screenshot of profiler is attached in the JIRA.
> Workaround:
> ===========
> Temp fix was to set "dfs.client.socketcache.capacity=1000" to prevent
> eviction.
> Added more debug logs revealed that multimap.size() was 40 instead of 20.
> LinkedListMultimap returns the total values instead of key size causing lots
> of evictions.
> {code}
> if (capacity == multimap.size()) {
> evictOldest();
> }
> {code}
> Should this be (capacity == multimap.keySet().size()) or is it expected that
> the "dfs.client.socketcache.capacity" be set to very high value?
> \cc [~gopalv], [~sseth]
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