[#XWIKI-287] c3p0 causes deadlock

XWiki Core

c3p0 causes deadlock

Created: 07/Jul/06 22:17 Updated: 27/Dec/06 16:47

Component/s:

Storage

Affects Version/s:

0.9.840

Fix Version/s:

1.0 B2

Environment:

« Hide

SunOS webtest2 5.9 Generic_118558-28 sun4u sparc SUNW,Sun-Fire-V240

keywords:	hibernate c3p0
Date of First Response:	22/Dec/06 14:34
Resolution Date:	27/Dec/06 16:47

Description

« Hide

I've been seeing Tomcat 5.5 lock up with this message:

WARN - ThreadPoolAsynchronousRunner$DeadlockDetector.run(429) |
com.mchange.v2.async.ThreadPoolAsynchron
ousRunner$DeadlockDetector@547c38 – APPARENT DEADLOCK!!! Creating emergency
threads for unassigned pend
ing tasks!

I found on the net that this is related to c3p0 pooling software and is fixed
in c3p0 0.9.0.2. I see that xwiki is using c3p0 0.8.

Do you think this is right?
thanks,
==Leonard

All

Comments

Change History

FishEye

Sort Order:

[ Permlink | « Hide ]

Ludovic Dubost added a comment - 22/Dec/06 14:34

These tasks need to be verified and put in the planning if these are bugs

[ Permlink | « Hide ]

Vincent Massol added a comment - 24/Dec/06 13:05

For more information on the problem see http://forum.hibernate.org/viewtopic.php?t=947246&highlight=apparent+deadlock+c3p0

We need to try using c3p0-0.9.1-pre11

[ Permlink | « Hide ]

Leonard Sitongia added a comment - 27/Dec/06 16:13

I happened to have recently resolved a similar situation in a different project. I was using a MySLQ JDBC driver mysql-connector-java-3.1.14-bin.jar with a MySQL server from 4.0. That gave me the same symptoms, using c3p0-0.9.1-pre11. When I backed off to mysql-connector-java-3.0.17-ga-bin.jar, the symptoms went away. This also fixed a problem I was seeing in which c3p0 wasn't keeping alive pooled connections using hibernate.c3p0.idle_test_period.

Probably the same thing is happening here. The install of Xwiki I have has mysql-connector-java-3.1.7-bin.jar and my site is using MySQL 4.0.

I bet this explains it: it is not compatible with MySQL 4.0.

I heard that MySQL 4.0 is no longer supported by mysql.com, and we are in the process of upgrading to 4.1, and beyond. So, perhaps this ticket should be closed indicating that Xwiki isn't compatible with MySQL 4.0 (due to c3p0).

==Leonard

[ Permlink | « Hide ]

Vincent Massol added a comment - 27/Dec/06 16:47

Thanks Leonard for the explanation! Closing the issue.

I have added the information on http://www.xwiki.org/xwiki/bin/view/AdminGuide/InstallationMySQL

-Vincent