×
The internal search function is temporarily non-functional. The current search engine is no longer viable and we are researching alternatives.
As a stop gap measure, we are using Google's custom search engine service.
If you know of an easy to use, open source, search engine ... please contact support@midrange.com.
Hi Lim,
First, the bad news: Assuming the classic JVM, GC normally runs
concurrently in an asynchronous thread. That means other work goes on
during a collection. In a "stop the world" collection, nothing else happens
until the collection is done. That means the app/web server appears
unresponsive during the collection cycle. If you had to find out via a
verbose log, either no one uses the applications(s) - unlikely, given the
typical causes - or they are just accustomed to poor performance.
It's easy to give the general causes, but can be a real bear to figure
out specifics.
- A burst of massive memory requests
- One or more memory leaks that overwhelm available memory over time
- Available CPU can't complete gc or can't complete in a timely manner.
This last could actually be some combination of CPU and page swapping, where
the JVM is effectively thrashing. .
As you can probably see, the causes can vary from scability isues to
program problems to application architecture. More bad news is that while
monitoring can help, unless it's a build up over time ( leak ), you probably
won't be able to get a dump or snapshot when you need it most.
Joe Sam
Joe Sam Shirah -
http://www.conceptgo.com
conceptGO - Consulting/Development/Outsourcing
Java Filter Forum:
http://www.ibm.com/developerworks/java/
Just the JDBC FAQs:
http://www.jguru.com/faq/JDBC
Going International?
http://www.jguru.com/faq/I18N
Que Java400?
http://www.jguru.com/faq/Java400
----- Original Message -----
From: "Lim Hock-Chai" <Lim.Hock-Chai@xxxxxxxxxxxxxxx>
To: "Java Programming on and around the iSeries / AS400"
<java400-l@xxxxxxxxxxxx>
Sent: Tuesday, March 03, 2009 4:07 PM
Subject: starting collection, reason stop the world collection
We turned on the *VERBOSEGC option on our web server and we see the
following message in the log :"starting collection, reason stop the
world collection". Does anybody know why the GC is stopping the world
when doing garbage collection? Is there a way to prevent this? Is this
control by the application or is this a standard JVM runtime function?
thanks
--
As an Amazon Associate we earn from qualifying purchases.