memory problems with tomcat

["Zeh, Christoph" <Ch...@TechniData.de>]

 <<jProfiler.jpg>> 

Hi, 

my problem is, that my webapplication allocates too much memory, while
running a stresstest using jmeter on a tomcat 4.1.18. This always ends in an
OutOfMemoryException. First i thougt of a memory leak, but when i checked
the heap, i found some strange scenario.
I took a screenshot  from jProfiler, which i attached to this mail, to
explain in detail.

I have set the maximum heapsize to the default value of 64 MB. 


Now the strange thing is, that although the garbage collector seems to do
his job well (the line which i marked with level 1 is mostly reached after
running gc) and the haepsize doesn' t grow much higher than the 
64 MB the VM takes more and more memory from the operating system. So when i
start the application the java.exe takes at about 50 MB of virtual memory,
but after some time the virtual memory goes up to 450 MB and more till the
webserver crushes. And all this with a constant heap size of about 60 MB.
Has anybody an idea what causes the VM not to give back the memory to the
operating system? Or is this a windows 2000 problem? 
I run the application on windows 2000 with tomcat 4.1.18 and sdk 1_4_0_03 

I hope somebody has experience with such a scenario.

Thank you

Christoph Zeh