Bug 969126 - Prevent possible deadlock in logging handlers when two threads invoke the error handler
Prevent possible deadlock in logging handlers when two threads invoke the err...
Product: JBoss Enterprise Application Platform 6
Classification: JBoss
Component: Logging (Show other bugs)
Unspecified Unspecified
unspecified Severity unspecified
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Assigned To: James Perkins
Depends On:
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Reported: 2013-05-30 13:32 EDT by Kyle Lape
Modified: 2014-08-19 12:19 EDT (History)
2 users (show)

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Doc Type: Bug Fix
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Last Closed: 2014-08-19 12:19:00 EDT
Type: Bug
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Description Kyle Lape 2013-05-30 13:32:42 EDT
There is a potential to have a deadlock if two threads are invoking logging handlers and both threads end up invoking the error handler for their logging handler.  

The way the deadlock works is 

- Thread 1 invokes the error handler
- The error handler writes to System.out.println
- This is routed back into the logging subsystem via jboss-stdio
- As usual, JBoss LogManager will send the message to all appropriate handlers
- The thread halts, waiting on a lock for the handler locked by thread 2

- Thread 2 is running in a different handler for which it has a lock
- This lock must have been obtained after thread 1 invoked this handler but before the error handler from thread 1 tried to invoke the same handler
- This handler also invokes its error handler
- The error handler halts, waiting on the lock for System.out, held by thread 1
Comment 2 James Perkins 2013-08-27 13:42:13 EDT
I think this relates to https://bugzilla.redhat.com/show_bug.cgi?id=961702 and has been fixed in the LogManager by using the org.jboss.logmanager.errormanager.OnlyOnceErrorManager. The JIRA was LOGMGR-65 and the LogManager PR was https://github.com/jboss-logging/jboss-logmanager/pull/18. This fix made it into jboss-logmanager-1.4.3.Final which made it into EAP 6.1.1.

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