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From "Doug Kelly (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DIRMINA-1021) MINA-CORE does not remove sessions if exceptions occur while closing
Date Sat, 05 Dec 2015 02:45:11 GMT

    [ https://issues.apache.org/jira/browse/DIRMINA-1021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15042604#comment-15042604
] 

Doug Kelly commented on DIRMINA-1021:
-------------------------------------

Hi Emmanuel,

I've been continuing to look into this (but I've been sidetracked over the past week), but
I was having issues reproducing and trapping the bug in a debugger again.  I was able to pretty
simply reproduce the issue with Gerrit (which is far more than a simple test application),
but if you want help getting that test environment set up so you can debug locally, please
let me know!

I'll try to dedicate some more time to this issue, since it is important to me (and I appreciate
the time you've given it), so please let me know if there's anything I can do.

> 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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