[ http://issues.apache.org/jira/browse/DIRMINA-65?page=all ]
Trustin Lee updated DIRMINA-65:
-------------------------------
Fix Version: 0.7.3
Version: 0.7.1
0.7
> Duplicate entries in flush-list, consequent unnecessary system-calls and
> overzealous wakeups and calls to write(2)
> ------------------------------------------------------------------------------------------------------------------
>
> Key: DIRMINA-65
> URL: http://issues.apache.org/jira/browse/DIRMINA-65
> Project: Directory MINA
> Type: Bug
> Versions: 0.7.2, 0.7.1, 0.7
> Environment: All
> Reporter: Mark Atwell
> Assignee: Trustin Lee
> Fix For: 0.7.3
> Attachments: SocketIoProcessor.java
>
> The following shows up under heavy load - writing numerous small messages
> across a slow(ish) network and/or to a slow peer i.e. when a writer starts to
> see back-log and writes don't necessarily complete.
> In SocketIoProcessor:
> - scheduleFlush() blindly adds the session to the queue even if it is already
> present. This means that when the selector thread wakes up it may make
> numerous calls to (relatively slow) write on the same session.
> - flushSession() calls scheduleFlush() and always wakes up the selector
> thread. This means that flushSessions() and flush() is called for each
> application write - even when the socket may already be backed up with queued
> traffic. This is exacerbated by the problem above.
> - scheduleFlush() is called from flushSession() which is called from (at
> least) SocketSessionManagerFilterChain for every application write.
> I 'hacked' a test fix which modified scheduleFlush() to only add the session
> if it wasn't already in the queue and returns a boolean indicating whether
> the session was added. flushSession() checks this return value and only wakes
> the selector thread if the session has been added (i.e. it isn't already
> backed up). In this way writes are not unnecessarily triggered.
> This worked though it also highlighted (or brought into greater focus? :o) an
> apparent timing problem.
> java.io.IOException: Invalid argument
> at sun.nio.ch.DevPollArrayWrapper.registerMultiple(Native Method)
> at
> sun.nio.ch.DevPollArrayWrapper.updateRegistrations(DevPollArrayWrapper.java:209)
> at sun.nio.ch.DevPollArrayWrapper.poll(DevPollArrayWrapper.java:157)
> at sun.nio.ch.DevPollSelectorImpl.doSelect(DevPollSelectorImpl.java:68)
> at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
> at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
> at
> org.apache.mina.io.socket.SocketIoProcessor$Worker.run(SocketIoProcessor.java:562)
> This isn't fatal though as the retry logic means that the next time 'round
> the state - presumably of the selection keys - has been brought into
> alignemnt?
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