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https://issues.apache.org/jira/browse/HDFS-9520?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rajesh Balamohan updated HDFS-9520:
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Attachment: HDFS-9520.png
> 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. Ideally it should not be evicting the connections since
> "dfs.client.socketcache.capacity" is set to 20 (no. of DN). 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()) ?
> \cc [~gopalv], [~sseth]
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