[jira] [Commented] (HBASE-24155) When running the tests, a tremendous number of connections are put into TIME_WAIT.

["Mark Robert Miller (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-24155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17079417#comment-17079417 ] 

Mark Robert Miller commented on HBASE-24155:
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I've got some notes, comments, questions, but one thought is that, given the number of connections, I'm wondering if this could be such a high problem if there was a lot of connection reuse going on. Some tests appear to make *way* more connections that I'd expect with reuse/pooling.

> When running the tests, a tremendous number of connections are put into TIME_WAIT.
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-24155
>                 URL: https://issues.apache.org/jira/browse/HBASE-24155
>             Project: HBase
>          Issue Type: Test
>          Components: test
>            Reporter: Mark Robert Miller
>            Priority: Major
>
> When you run the test suite and monitor the number of connections in TIME_WAIT, it appears that a very large number of connections do not end up with a proper connection close lifecycle.
> Given connections can stay in TIME_WAIT from 1-4 minutes depending on OS/Env, running the tests faster or with more tests in parallel increases the TIME_WAIT connection buildup. Some tests spin up a very, very large number of connections and if the wrong ones run at the same time, this can also greatly increase the number of connections put into TIME_WAIT. This can have a dramatic affect on performance (as it can take longer to create a new connection) or flat out fail or timeout.
> Ideally, a small proportion of connections in a test suite would end up in TIME_WAIT in comparison to the number created.
> Notes to come in comments below.



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