Doug Kelly created DIRMINA-1021:
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Summary: 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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