What can cause high cpu usage in java?

[mk]

Hi,

what can cause a high cpu usage on a linux server with tomcat and
jdk1.4.1_02?
Our webapplication is unused and the logs of the garbage collector
tell us, that
even the garbage collector seems to be bored; i.e. it works about
every 300 sec.

Nonetheless we have a couple of low prioritized java processes which
share almost the whole cpu (about 90%).

What is java doing when even the garbage collector seems to have
nothing to do?
What can be logged from the VM besides the garbage collector
activities to
gain more information?

Help is urgent, since the system can only be relieved through a tomcat
restart.

Thanks,

Markus

 

[Robert Olofsson]

Roger Irwin ([email protected]) wrote:
: mk wrote:
: > Hi,
: >
: > what can cause a high cpu usage on a linux server with tomcat and
: > jdk1.4.1_02?

: Java (and any other language), will continue to use the CPU if you put
: it in a loop, which frequently happens when polling is used to wait for
: a condition. example:

: while(1){
: if(PollTest==1)break;
: }

And if you have context reloading on tomcat will run a loop quite often.
Try turning it off, it should only be used for development.

/robo