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https://issues.apache.org/jira/browse/DIRMINA-1021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15043714#comment-15043714
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Emmanuel Lecharny commented on DIRMINA-1021:
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yes, but...
what happens is that {{isClosing}} simply means the session is scheduled for
closing, not actually closed. The rationnal being that some data might be still
waiting to be sent, and because the server has decided to close the session
does nit necessarily implies those data to be discarded.
In this very case, we have got an exception, mostly because the client is not
there anymore, thus there is no reason to wait for the pending data to be kept
in memory and for the session to remain in this state forever. This is why it's
good to close the session immediately when an exception is caught.
> MINA-CORE does not remove sessions if exceptions occur while closing
> --------------------------------------------------------------------
>
> Key: DIRMINA-1021
> URL: https://issues.apache.org/jira/browse/DIRMINA-1021
> Project: MINA
> Issue Type: Bug
> Affects Versions: 2.0.8
> Environment: mina-ssh 0.14.0
> mina-core 2.0.8
> Multiple OSes / Java configurations:
> * Mac OS X El Capitan on Java 8 (1.8.0_60)
> * CentOS 6.4 on Java 8 (1.8.0_60)
> * CentOS 6.5 on Java 8 (1.8.0_20-b26).
> Reporter: Doug Kelly
> Attachments: attempt-removing-sessions-closing.patch
>
>
> MINA SSHD isn't removing sessions when using the MINA/NIO backend if an
> exception as received as the session is closing (such as a connection reset
> is received with data still in the write buffer). When this case happens, it
> seems that {{NioProcessor.getState}} returns the state as {{CLOSING}} (I'm
> assuming since the underlying channel is now closed), which means that the
> {{AbstractPollingIoProcessor.removeSessions()}} won't ever prune the session,
> since a {{CLOSING}} state is simply ignored. The result is a resource leak
> over time, since these sessions are never pruned (it's a slow leak, since
> entering this condition is racy – on my workstation, I can produce it through
> randomly interrupting connections anywhere from 1/6 to 1/10th of the time).
> (This may either be major or critical; reprioritize as necessary.)
> I specifically see this error with Gerrit 2.10.4 and Gerrit 2.11.5 (using
> mina-sshd 0.14.0 / mina-core 2.0.8), and it looks like the code path is
> unchanged in mina-sshd 1.0.0 / mina-core 2.0.9. I was unsure if this is
> specifically a bug in mina-core or, if it's something unique to mina-sshd. My
> local development system runs Mac OS X El Capitan on Java 8 (1.8.0_60), but
> I've also seen this on Linux (CentOS 6.4, again Java 1.8.0_60 and CentOS 6.5
> on Java 1.8.0_20-b26).
> The fix may be as simple as attempting to remove the session if {{OPENED}} or
> {{CLOSING}}, but I'm unsure what side-effects this may have with other
> backends. I'll be happy to test it locally, but I'm fairly ignorant when it
> comes to MINA's code.
> The attached patch (to mina-core) seems to resolve the issue by following the
> reproduction case I have on the [Gerrit issue
> tracker|https://code.google.com/p/gerrit/issues/detail?id=3685].
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