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From "Christopher L. Shannon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMQ-5712) Broker can deadlock when using queues while producers wait on disk space
Date Mon, 13 Apr 2015 19:23:14 GMT

    [ https://issues.apache.org/jira/browse/AMQ-5712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14492920#comment-14492920
] 

Christopher L. Shannon commented on AMQ-5712:
---------------------------------------------

As Timothy said, PFC doesn't make a difference and we have tried it both on and off.  For
now we have the producer switched to being persistent to fix the issue temporarily. {{forcePersistencyModeBrokerPlugin}}
doesn't really help because we want to be able to support both persistent and non-persistent
messages on the same destination and don't want to enforce what the producer sets the delivery
mode as. 

> Broker can deadlock when using queues while producers wait on disk space
> ------------------------------------------------------------------------
>
>                 Key: AMQ-5712
>                 URL: https://issues.apache.org/jira/browse/AMQ-5712
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.11.1
>            Reporter: Christopher L. Shannon
>
> I am experiencing a deadlock when using a Queue with non-persistent messages.  The queue
has a cursor high memory water mark set (right now at 70%).  When a producer is producing
messages quickly to the queue and that limit gets hit, the broker can deadlock.   I have tried
setting producerWindowSize and alwaysSyncSend which did not seem to help. When the broker
hits that limit, I am unable to do things like purge the queue.  Consumers can also deadlock
as well. 
> Note that this appears to be the same issue as described in this ticket here: AMQ-2475
.  The difference is that I am using a Queue and not a Topic and the fix for this appears
to only have been for Topics.
> The problem appears to be in the Queue class on line 1852 inside the {{cursorAdd}} method.
 The method being called is {{return messages.addMessageLast(msg);}} which will block indefinitely
if there is no space available, which in turn ties up the {{messagesLock}} from being used
by any other threads.  We have seen a deadlock where consumers can't consume because they
are waiting on this lock.   It looks like in AMQ-2475 part of the fix was to replace {{messages.addMessageLast(msg)}}
with {{messages.tryAddMessageLast(msg, 10)}}.  I also noticed that not all of the message
cursors support {{tryAddMessageLast}}, which could be a problem.  {{FilePendingMessageCursor}}
implements it but the rest of the cursors (notably {{StoreQueueCursor}}) simply delegate back
to {{addMessageLast}} in the parent class.  So part of this fix may require implementing {{tryAddMessageLast}}
across more cursors.
> Here is part of the thread dump showing the stuck producer:
> {code}
> "ActiveMQ Transport: ssl:///192.168.3.142:38589" daemon prio=10 tid=0x00007fb46c006000
nid=0x3b1a runnable [0x00007fb4b8a0d000]
>    java.lang.Thread.State: TIMED_WAITING (parking)
>         at sun.misc.Unsafe.park(Native Method)
>         - parking to wait for  <0x00000000cfb13cd0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
>         at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226)
>         at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2176)
>         at org.apache.activemq.usage.Usage.waitForSpace(Usage.java:103)
>         at org.apache.activemq.usage.Usage.waitForSpace(Usage.java:90)
>         at org.apache.activemq.usage.Usage.waitForSpace(Usage.java:80)
>         at org.apache.activemq.broker.region.cursors.FilePendingMessageCursor.tryAddMessageLast(FilePendingMessageCursor.java:235)
>         - locked <0x00000000d2015ee0> (a org.apache.activemq.broker.region.cursors.FilePendingMessageCursor)
>         at org.apache.activemq.broker.region.cursors.FilePendingMessageCursor.addMessageLast(FilePendingMessageCursor.java:207)
>         - locked <0x00000000d2015ee0> (a org.apache.activemq.broker.region.cursors.FilePendingMessageCursor)
>         at org.apache.activemq.broker.region.cursors.StoreQueueCursor.addMessageLast(StoreQueueCursor.java:97)
>         - locked <0x00000000d1f20908> (a org.apache.activemq.broker.region.cursors.StoreQueueCursor)
> {code}



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