Can the Weblogic Server trigger the GC after the free heap space falls below a certain limit?

Hi ,

I am using WLS 10.3.2 and IBM AIX 6 as the OS and IBM jdk.

The application running on the server hanged after the gc did not happen even after the free heap space falls to 0%. This condition where the gc did not happen even if the free heap space dropped to 0% remained for another 40 min. I had to restart the box to start the application again.

I was manually able to trigger gc through the console's Garbage Collect button. As soon as I pressed the Garbage Collect button, the free heap % shoots up to 90.The jvm garbage collected and freed the heap space.

This did happen but is there any way that through the WLS server I can make the GC to happen after the free heap space falls below a certain limit?

After a little research I found an option for the setDomainEnv.sh:

-XX:MinHeapFreeRatio & -XX:MaxHeapFreeRatio. Can this tag help the WLS to trigger GC to happen at a particular free heap space ratio?

What are these option used for?

Any guidance or clue could be very helpful.

the issue occurred again and the application deployed on the server stopped responding...... any help or clue what's happening?

Sam Pablo wrote:IBM jdk ...

After a little research I found an option for the setDomainEnv.sh:

-XX:MinHeapFreeRatio & -XX:MaxHeapFreeRatio

These are Sun's JVM switches, for IBM JVM you should use -Xminf, -Xmaxf

Misha Ver wrote:

These are Sun's JVM switches, for IBM JVM you should use -Xminf, -Xmaxf

Hey, thanks Misha

. Have you used this tag? Is this to be included in the setDomainEnv.sh java options?

Thank you for the reply

What are the parameters that are to be specified? Is it a ratio like 40 and 70 or something else? Please help.

Refer to this for the values of the parameters.

Parameter Values

Hope this helps.

-XX:MaxHeapFreeRatio= -- Maximum percentage of heap free after GC to avoid shrinking.
-XX:MinHeapFreeRatio= -- Minimum percentage of heap free after GC to avoid expansion.

Please check this out

http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp

Joseph Antoine Raja wrote:-XX:MaxHeapFreeRatio= -- Maximum percentage of heap free after GC to avoid shrinking.
-XX:MinHeapFreeRatio= -- Minimum percentage of heap free after GC to avoid expansion.

Please check this out

http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp

These are Sun's JVM switches, Sam Pablo is using IBM JVM. See my post above.