Question

JAVA goes beyond the JAVA memory allocation

Asked by: rbtt

I am currently running a JAVA process on my LINUX server.

I have allocated 256m of memory to my java process (Xmx256), but the JAVA processes utilises much more memory. The processes use as much as 600m.

Is there an explanantion for this?

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Asked On
2008-02-18 at 09:04:10ID23171869
Tags

JAVA

Topics

Java Application Servers

,

Web Development Software

,

Server Software

Participating Experts
1
Points
250
Comments
7

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Answers

 

by: evguenPosted on 2008-02-18 at 09:09:55ID: 20921598

Hello,

could you please explain how you get this result ?

Could you please execute
$> ps aux | grep java

Best regards

 

by: rbttPosted on 2008-02-18 at 09:14:00ID: 20921638

I am getting this result by using the LINUX top command.

Is this the correct way to monitor the java memory?

 

by: evguenPosted on 2008-02-18 at 09:17:34ID: 20921671

It depends the column you're looking on.
What gives you :
$> ps aux | grep java
?

 

by: rbttPosted on 2008-02-18 at 09:20:35ID: 20921694

[root@vinbrsvr01 ~]# ps aux | grep java
t24prd   16471  0.0  0.7 608936 29620 ?      Sl   Feb04   1:26 java -Xmx256M -Djava.endorsed.dirs=../lib/endorsed/jaxp13:../lib/endorsed/jaxb13 -jar ../lib/tcserver.jar -d
root      2359  1.3  9.5 1010624 383844 ?    Sl   08:56   3:37 /usr/java/java/bin/java -Xms512M -Xmx1024M -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=/opt/tomcat/conf/logging.properties -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=8050 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Xms256M -Xmx600M -Djava.endorsed.dirs=/opt/tomcat/common/endorsed -classpath :/opt/tomcat/bin/bootstrap.jar:/opt/tomcat/bin/commons-logging-api.jar -Dcatalina.base=/opt/tomcat -Dcatalina.home=/opt/tomcat -Djava.io.tmpdir=/opt/tomcat/temp org.apache.catalina.startup.Bootstrap start
root      3095  0.0  0.0 51088  684 pts/4    S+   13:30   0:00 grep java

 

by: evguenPosted on 2008-02-18 at 09:34:31ID: 20921821

For your first Java process in the list, you have :
608936  of virtual memory (size in Kbytes)
29620 of real memory (resident set) (size of the process in Kbytes).

So, your programm is currently using 29Mo of memory.

Hope this helps

Best regards

 

by: evguenPosted on 2008-02-18 at 10:13:06ID: 20922114

Thank you for the points.

In the ps man, you can have a look at VMZ and RSS as an input on this subject.

Best regards

 

by: rbttPosted on 2008-02-18 at 10:19:31ID: 20922159

Another question. If I have a JAVA maximun allocation of 256M, we are seeing virtual memory usage of over 600M. Is this virtual memory only for the JAVA process or for the entire server?

Also if this virtual memory is for this java process, why does it cross 256m?

Thanks.

20120131-EE-VQP-002

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