Bugs item #745527, was opened at 2003-05-29 14:30
Message generated for change (Comment added) made by ejort
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=376685&aid=745527&group_id=22866

Category: JBossMQ
Group: None
>Status: Closed
>Resolution: Out of Date
Priority: 5
Submitted By: john hutchinson (jamoville)
>Assigned to: Adrian Brock (ejort)
Summary: race condition with BasicQueue

Initial Comment:
This bug exists in all versions of jboss 3.X. and on Unix 
and windows

I have an application that utilizes messaging to a great 
extent.  When running many threads against your server 
a deadlock occurs.  I ended up dumping the threads and 
windows informed me of a race condition with 
BasicQueue.  Specifically one thread was waiting on a 
monitor that was already held by another thread and that 
thread was waiting on a monitor that the other thread 
had.  The synchronized objects where 
unacknowledgedMessages and removedSubscribers.  If 
needed I can supply the stack dump of both threads.  I 
corrected this by removing all synch blocks in the 
BasicQueue class and any method that contained a 
synch block I made synchronized.  This fixed the issue 
and gave the added benifit of increasing performance by 
30 to 40 percent.  I've attached the modified file

----------------------------------------------------------------------

>Comment By: Adrian Brock (ejort)
Date: 2003-05-29 15:07

Message:
Logged In: YES 
user_id=9459

Hi,

This has already been fixed in cvs.

http://cvs.sourceforge.net/cgi-
bin/viewcvs.cgi/jboss/jbossmq/src/main/org/jboss/mq/server/B
asicQueue.java.diff?r1=1.20.2.8&r2=1.20.2.9

As I have already noted in the source the synchronization
needs tidying up. 
Removing it is not an option,
unless you don't care about loosing messages
and concurrent access.

Regards,
Adrian

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=376685&aid=745527&group_id=22866


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