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How do I change the Java heapsize?


Sandra Bernspang (1548) | asked Oct 08 '12, 8:12 a.m.
JAZZ DEVELOPER
I have an installation with JTS, RTC, RRC, and RQM + RSA/DM, running in a VMWare image for demo purposes. I want to increase the Java heapsize to improve performance. How do I do that?

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Philippe Mulet (55112) | answered Oct 18 '12, 4:12 a.m.
FORUM MODERATOR / JAZZ DEVELOPER
Instead of touching the catalina.bat, you should rather edit <install dir>/server/server.startup.bat (or shell script)
Look for these lines, and edit them to meet your needs:

set JAVA_OPTS=%JAVA_OPTS% -Xmx4G
set JAVA_OPTS=%JAVA_OPTS% -Xms4G
set JAVA_OPTS=%JAVA_OPTS% -Xmn512M

Try to keep max (-Xmx) heap == min (-Xms) heap, and nursery size (-Xmn) to 1/8 of max heap.
Sandra Bernspang selected this answer as the correct answer

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Sandra Bernspang commented Oct 18 '12, 5:03 a.m.
JAZZ DEVELOPER

Thank you, Philippe.

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Anderson Oliveira Pinto (1701614) | answered Oct 08 '12, 9:02 a.m.
Hi Sandra,

If you want increase Java heap size on websphere follow these steps below.

  1. Open the WebSphere Application Server administrative console, http://hostname:port/ibm/console , and log in.
  2. Expand Servers > Application servers > server1 > Java and Process Management > Process Definition > Java Virtual Machine.
  3. Change the Max Heap Size to a larger value.
  4. Click Apply and click Save at the top of this page.
  5. Restart WebSphere Application Server.
If you are using another application server let me know.

Tks
Anderson

Comments
Sandra Bernspang commented Oct 08 '12, 9:06 a.m. | edited Oct 18 '12, 9:15 a.m.
JAZZ DEVELOPER

Anderson, I'm using Tomcat.


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Michael Afshar (6514) | answered Oct 12 '12, 1:54 a.m.
JAZZ DEVELOPER
You can use this topic for reference http://pic.dhe.ibm.com/infocenter/clmhelp/v4r0/topic/com.ibm.jazz.install.doc/topics/t_run_rqm64_win_service.html


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Anderson Oliveira Pinto (1701614) | answered Oct 08 '12, 9:21 a.m.
Sandra, Try this

Use the environment variable CATALINA_OPTS or JAVA_OPTS in catalina.bat or catalina.sh to set JVM heap size.


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Sandra Bernspang commented Oct 08 '12, 10:39 a.m. | edited Oct 18 '12, 9:16 a.m.
JAZZ DEVELOPER

That's what I thought I needed to do, just wanted to see if there was a better (recommended) way than by editing the bat file.

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