Heap Size Question (Memory Usage)

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Hi,

I have a couple questions regarding heap sizes.

Below you can see the memory utilization of one of our profiles. All the applications on this profile are stopped but it seems that the application server is still utilizing memory every now and then. Is it because the profile itself is running? Why is the utilization not stable and is still reaching peaks even though all applications are stopped?
img.photobucket.com/albums/v702/JRyan/he...

Another question: in the above image, the initial heap size was set to 256 and it was almost reaching the peak. So we set the initial heap size to 512 but the the peak was still almost reached. Why did the memory utilization also went up when we adjusted the initial heap size to a higher value?
img.photobucket.com/albums/v702/JRyan/he...


Thanks in advance to everyone!

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Posted By: jay_ry18 at Aug 6 2009 8:34AM

Hard to say without more info. The appserver is really just an application to the JVM and will allocate objects on the heap, but it if truly is the only thing running, this would seem rather unusual.

For the second part, this seems normal. Objects will continue to be allocated until there is not enough contiguous space on the heap to fulfill the allocation request. Then gc will kick in and remove the 'dead' objects. If the heap is larger, you will be able to allocate more objects (and use more of the heap) before hitting that point.

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Posted By: cathy at Aug 8 2009 11:42AM