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From "Chris Hofstaedter" <>
Subject RE: Deadlock in MutexTransport on shutdown with high volume of messages
Date Fri, 05 Jan 2007 14:51:00 GMT
Created AMQ-1119

-----Original Message-----
From: Chris Hofstaedter [] 
Sent: Thursday, January 04, 2007 11:47 AM
Subject: Deadlock in MutexTransport on shutdown with high volume of

I ran into a deadlock in the MutextTransport.oneway(Command command)
function when processing very high message volume (100% cpu utilization)
at the time of a shutdown.  I'm running 4.0.2 on WinXP and within a
demand forwarding environment with failover = true.
I did trap this deadlock in the debugger and it looks like two commands
are crossing paths in opposite directions through the MutexTransport.
One of the commands is a MessageDispatch and the other is a
ShutdownInfo.  Now, when the ShutdownInfo gets through the
MutexTransport first, it tries to shutdown the background thread of the
TcpTransport.  However, this thread is currently servicing the
MessageDispatch and is blocked on the MutexTransport.  Deadlock.
So, my patch was simply to avoid entering the synchronized(writeMutex)
block in the oneway(Command command) function of MutexTransport if
command.isShutdownInfo() returns true:
if (command.isShutdownInfo())
   synchronized(writeMutex)  {
Let me know if you think this is an appropriate patch and you'd like me
to create a JIRA on this or not.

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