OutOfMemoryError below max heap

[Travis Kline]

Hi All,
I have an application that periodically gets OutOfMemoryErrors when under heavy volume. The application has a max heap setting of 512mb but will experience OutOfMemoryErrors when the free memory/allocated memory is 256mb. Most times the application will then be granted more memory, but sometimes it just hangs.
Is anyone familiar with WebSphere's process for allocating memory to application instances? If the max heap size is set to 512mb, is that reserved for the application? I have also heard people mention "paging" when discussing garbage collection and memory, how does this process work? Thanks for any help....
Travis

[Vinod Bijlani]

did you check whts the mem utilization on the box when websphere hangs??

[Tony Chen]

Originally posted by Travis Kline:
The application has a max heap setting of 512mb but will experience OutOfMemoryErrors when the free memory/allocated memory is 256mb.

Travis,
What's the init heap size? Is it also 512mb? If so, change it to 128mb. It seems to me that the heap was fragmented by some "unmovable" objects allocated to the 512mb.
Tony