Heap allocation problem

Question

Hi all,
I have a strange heap allocation problem with my application. I will try to explain what happens:
My AWT-application reads data every second from a serial port and displays it. Max. heap size is set to -Xmx32m because the application has to run in an environment with little memory. JVM is 1.4.2_18.
After some hours I get an OutOfMemoryError. My first idea of course was: ok a memory leak, use my profiler and see what happens. But I can not find any memory leaks. The following is what I can see in my profiler:
The first 2 hours everything seems to be OK. The available heap size is stable at 15 MB and the used heap goes up and down as normal. But after 2 hours the used heap size has some peaks. The used heap seems to build up and the peaks get higher but still the used heap size goes down due to GC until a peak is so high that it is over 32MB and my application dies. The recorded objects graph has the same trend as the heap graph. The VM seems to "forget" garbage collection...
The only idea I have is that heap fragmentation occurs e.g. because of array allocations. But until know all attempts to track down the problem failed.
Any ideas what can be the cause of the problem or what I can try? Any help is welcome.
Edited by: JBrain on Aug 21, 2008 12:40 AM
Edited by: JBrain on Aug 21, 2008 4:27 AM

Answer 1

Yes, the same limitation in 32-bit Linux applies to JRockit as well. On
a 64-bit architecture this limit does not exist.
Regards,
/Staffan
Andrew Kelly wrote:
Sun JDK bug 4435069 states that there is a limitation to the Heap size for a Linux
JDK of 2G.
Does this restriction also applie to JRocket, has this been tested?