setting JVM heap size in 64bit JVM

RE: setting JVM heap size in 64bit JVM

2012-07-18T07:19:04Z

Thanks Mika..

Mika Koivisto:

Heap is not absolute amount of memory your java process will take. There's several factors and I've quite recently explained them in my blog post: Why is my java process taking more memory than I gave it?

RE: setting JVM heap size in 64bit JVM

2012-07-13T15:56:06Z

Mika Koivisto:

The maximum heap certainly isn't 4GB on a 64bit system. You can increase it well beyond that but doing so may adversely affect the performance of the application because of longer full garbage collection times.

Must have been thinking 32 bit, thank you. GC is also tunable.

-XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:SurvivorRatio=20 -XX: ParallelGCThreads=8

RE: setting JVM heap size in 64bit JVM

2012-07-13T07:39:54Z

Hi Mika,

Good Sharing,
@Sreeraj : you can follow given formula.
(-Xmx) + (-XX:MaxPermSize) + numberofthreads * (-Xss) + Other mem

Thanks,
Sagar Vyas

RE: setting JVM heap size in 64bit JVM

2012-07-12T21:07:55Z

The maximum heap certainly isn't 4GB on a 64bit system. You can increase it well beyond that but doing so may adversely affect the performance of the application because of longer full garbage collection times.

RE: setting JVM heap size in 64bit JVM

2012-07-12T21:04:08Z

Heap is not absolute amount of memory your java process will take. There's several factors and I've quite recently explained them in my blog post: Why is my java process taking more memory than I gave it?

RE: setting JVM heap size

2012-07-12T18:24:20Z

I use apache bench or http_load if non-ssl to simulate a bunch of users banging on the site while monitoring the memory usage in jvisualvm remotely and adjust accordingly til I get the behavior desired.
Given your hardware I'd assume you'll need some resources for other apps like backup etc. and recommend for a starting point a setenv.sh of;

JAVA_OPTS="$JAVA_OPTS -XX:NewSize=700m -XX:MaxNewSize=700m -Xms2560m -Xmx2560m -XX:MaxPermSize=512m -Dfile.encoding=UTF8 -Duser.timezone=GMT -Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:SurvivorRatio=20 -XX: ParallelGCThreads=8"

concatenate this to the above string to enable JMX;

 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.port=33100

RE: setting JVM heap size

2012-07-12T13:55:32Z

Chintan Akhani:

As you have 6 GB memory allocated for liferay instance only, so you can increase heap size upto 4 GB.

Thanks for your reply. How you are telling 4GB? is there any procedure or best practices to determine the heap size value? Can you please explain..

RE: setting JVM heap size

2012-07-12T11:46:12Z

As you have 6 GB memory allocated for liferay instance only, so you can increase heap size upto 4 GB.

RE: setting JVM heap size

2012-07-12T10:14:53Z

Sreeraj AV:

Below is the system details. This server is dedicated to Liferay portal. I need to change the JVM heap size. Can anyone please tell me what is the optimal heap size i can provide for this particular JVM?

Processor: Intel(R) Xeon(R) CPU E5645 @ 2.40GHz , dual core- 64bit
Memory : 6GB
OS : Linux 64bit
Java : java version "1.6.0_21-ea" 64bit

Hi Sreeraj,

You can edit setenv.sh located in "tomcat-New\tomcat-6.0.32\bin"

-Xmx1024m -XX:MaxPermSize=256m" change it to -Xmx1024m -XX:MaxPermSize=512m"

Hope this help.

Thanks,
Sagar Vyas

setting JVM heap size in 64bit JVM

2012-07-12T09:55:50Z

Below is the system details. This server is dedicated to Liferay portal. I need to change the JVM heap size. Can anyone please tell me what is the optimal heap size i can provide for this particular JVM?

Processor: Intel(R) Xeon(R) CPU E5645 @ 2.40GHz , dual core- 64bit
Memory : 6GB
OS : Linux 64bit
Java : java version "1.6.0_21-ea" 64bit