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From Christian Posta <christian.po...@gmail.com>
Subject Re: Activemq 5.4.2 hangs when the temp disk usage is used
Date Mon, 17 Dec 2012 14:28:46 GMT
There's been a lot of re-work on the FilePendingMessageCursor (and other
areas that you touched here) since release 5.4.2 (which is about 2 yrs
old). Do you have the possibility to check with a later version of the code
to see if that's been fixed for you?




On Mon, Dec 17, 2012 at 6:36 AM, Tom Martinec <martinec@d3s.mff.cuni.cz>wrote:

> Hello,
>
> I fixed the issue on my own. Here is the list of things I have done:
>
> 1 - On the line 219 of
>
> http://svn.apache.org/viewvc/activemq/tags/activemq-5.4.2/activemq-core/src/main/java/org/apache/activemq/broker/region/cursors/FilePendingMessageCursor.java?view=markup
> I unlocked the messagesLock that was created in the queue. I have done
> that,
> because the writer thread waits for free space, but the consumers are
> locked
> waiting until the writer thread releases the lock.
>
>                 boolean spaceAvailable = waitForTempSpace(maxWaitTime);
>
>                 if (spaceAvailable) {
>                     ByteSequence bs = getByteSequence(node.getMessage());
>                     getDiskList().addLast(node.getMessageId().toString(),
> bs);
>                     return true;
>                 }
>                 return false;
>
>     protected boolean waitForTempSpace(long maxWaitTime) throws
> InterruptedException {
>         if (cursorLock != null) {
>                 cursorLock.writeLock().unlock();
>         }
>
>         boolean freeSpaceAvailable =
> systemUsage.getTempUsage().waitForSpace(maxWaitTime);
>
>         if (cursorLock != null) {
>                 cursorLock.writeLock().lock();
>         }
>
>         return freeSpaceAvailable;
>     }
>
> 2 - The writer and consumer threads are also synchronized on the object of
> the cursor. So the step 1) was not enough. IMHO only one of the
> synchronized
> primitive should be used. I decided to keep the RW lock that was created
> inside the Queue class. By the way, the advantage of RW locks seemed to
> never be used because of the second synchronization mechanism. This
> basically required to remove the "synchronized" keywords from the cursors
> and replace them by the RW lock from outside where the sync was still
> needed.
>
> 3 - There was yet another deadlock looking behaviour. The
> TempUsage.retrieveUsage() worked with full preallocated size of kahadb
> storage, so the storage was always considered full. I extended the kahadb
> interface to provide the count of free bytes in the PListStore and not just
> its size.
>
> Since then the ActiveMQ has been be working fine with no deadlocks. Note,
> that I use the ActiveMQ only in a simple Queuing scenario, so I could have
> broken something else by this change.
>
>
>
>
> --
> View this message in context:
> http://activemq.2283324.n4.nabble.com/Activemq-5-4-2-hangs-when-the-temp-disk-usage-is-used-tp4660202p4660746.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>



-- 
*Christian Posta*
http://www.christianposta.com/blog
twitter: @christianposta

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