[Deploying Sakai] [Building Sakai] Production Problems with Garbage Collection

mizematr at notes.udayton.edu mizematr at notes.udayton.edu
Fri Jan 21 06:37:59 PST 2011

When we were having Java GC problems, I found visualgc to be very useful 
for monitoring the heap structure and performance in real-time.  It's part 
of the jvmstat tool set, available here: 
Matt Mize, Systems Administrator
 - Pay no attention to the man in the back office....
Matt.Mize at notes.udayton.edu
(937) 229-1024

UDit Department, University of Dayton
300 College Park, Dayton, OH, 45469-1302

From:   Beth Kirschner <bkirschn at umich.edu>
To:     "sakai-dev at collab.sakaiproject.org Sakai-Dev" 
<sakai-dev at collab.sakaiproject.org>, production at collab.sakaiproject.org
Date:   01/20/2011 12:16 PM
Subject:        [Building Sakai] Production Problems with Garbage 
Sent by:        sakai-dev-bounces at collab.sakaiproject.org

Hi all,

  We've been looking into some serious production problems which have 
required frequent restarting of our production servers due to the 
performance impact of the server being mired in continuous Garbage 
Collection. The only clue we have from the logs is "Concurrent Mode 
Failure" messages in logs. These problems started shortly after updating 
to Java 1.6 and Sakai 2.7.1.

  I'm looking for help and advice, specifically: Has anyone seen these 
types of issues in Sakai production?

  On a related note, I'm wondering if anyone has specific diagnostic tools 
that they use for production Sakai systems, to allow for better analysis 
of: heap dumps, thread dumps, tomcat monitoring (e.g. psi-probe, jstack, 
jconsole, visualvm), and log file analysis (e.g. swatch)?

- Beth
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