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Date: Thu, 12 Mar 2015 12:47:38 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (AMQ-5659) Add safety measure against infinite
 loop when store exception prevents message removal
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    [ https://issues.apache.org/jira/browse/AMQ-5659?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358604#comment-14358604 ] 

ASF GitHub Bot commented on AMQ-5659:
-------------------------------------

GitHub user metatechbe opened a pull request:

    https://github.com/apache/activemq/pull/71

    AMQ-5659 Safety measure against infinite loop in "purge"

    
You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/metatechbe/activemq patch-2

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/activemq/pull/71.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #71
    
----
commit df703832a308d44d5a166e96aaf89876d4f19552
Author: metatechbe <metatechbe@gmail.com>
Date:   2015-03-12T12:46:56Z

    AMQ-5659 Safety measure against infinite loop in "purge"

----


> Add safety measure against infinite loop when store exception prevents message removal
> --------------------------------------------------------------------------------------
>
>                 Key: AMQ-5659
>                 URL: https://issues.apache.org/jira/browse/AMQ-5659
>             Project: ActiveMQ
>          Issue Type: Improvement
>          Components: Broker
>    Affects Versions: 5.7.0
>         Environment: ServiceMix 4.5.3
>            Reporter: metatech
>         Attachments: purge_queue_abort_loop.patch
>
>
> When the broker is configured with a database store, the "purge" operation enters an infinite loop when the message removal operation fails, for instance when the broker datasource is being restarted (see example stack trace below). 
> Here is a patch which adds a safety measure, in case the "dequeue" count of the queue does not increase between 2 messages removal operations.  The check is not garanteed to detect the problem on the next iteration, because a business consumer might also be dequeuing messages from the queue.  But the "purge" is probably much faster than the business consumer, so if it fails to remove 2 messages in a row, it is enough to detect the problem and abort the infinite loop.
> {code}
> 2015-03-05 15:38:30,353 | WARN  | 14571659-2202099 |  | JDBCPersistenceAdapter           | Could not get JDBC connection: Data source is closed
> java.sql.SQLException: Data source is closed
> 	at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1362)
> 	at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
> 	at org.apache.activemq.store.jdbc.TransactionContext.getConnection(TransactionContext.java:58)
> 	at org.apache.activemq.store.jdbc.adapter.DefaultJDBCAdapter.getStoreSequenceId(DefaultJDBCAdapter.java:285)
> 	at org.apache.activemq.store.jdbc.JDBCPersistenceAdapter.getStoreSequenceIdForMessageId(JDBCPersistenceAdapter.java:787)
> 	at org.apache.activemq.store.jdbc.JDBCMessageStore.removeMessage(JDBCMessageStore.java:194)
> 	at org.apache.activemq.store.memory.MemoryTransactionStore.removeMessage(MemoryTransactionStore.java:358)
> 	at org.apache.activemq.store.memory.MemoryTransactionStore$1.removeAsyncMessage(MemoryTransactionStore.java:166)
> 	at org.apache.activemq.broker.region.Queue.acknowledge(Queue.java:846)
> 	at org.apache.activemq.broker.region.Queue.removeMessage(Queue.java:1602)
> 	at org.apache.activemq.broker.region.Queue.removeMessage(Queue.java:1594)
> 	at org.apache.activemq.broker.region.Queue.removeMessage(Queue.java:1579)
> 	at org.apache.activemq.broker.region.Queue.purge(Queue.java:1158)
> 	at org.apache.activemq.broker.jmx.QueueView.purge(QueueView.java:54)
> {code}


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