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Posted to notifications@couchdb.apache.org by "Benjamin Anderson (JIRA)" <ji...@apache.org> on 2016/04/10 05:57:25 UTC

[jira] [Created] (COUCHDB-2984) mem3_sync event listener performance degrades with high q values

Benjamin Anderson created COUCHDB-2984:
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             Summary: mem3_sync event listener performance degrades with high q values
                 Key: COUCHDB-2984
                 URL: https://issues.apache.org/jira/browse/COUCHDB-2984
             Project: CouchDB
          Issue Type: Improvement
            Reporter: Benjamin Anderson


High throughput applications on databases with high (300+) q values have a tendency to cause very poor performance. While I don't fully understand the issue at hand, one clear manifestation is in mem3_sync's event listener. With high q values, the shard "selection" routine (the <<"shards/",·_/binary>> head of handle_event/3) will bottleneck on calls to mem3_shards:for_db/1 due to the large (tens of KB) shard maps in ETS.



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