Heap Size getting increased without any users
Seeing heap size alert in of the production server, currently there is no user but still they are able to see the usage more than 90%.
Heap size threshold increased and it is more than 90%
Steps to Reproduce
Analysis of heaps dumps showed very low heap usage - no issue.
Unsure what alerts were occurring, but the act of producing a heap dump or thread dump had triggered gc, which cleared memory and showed the heap was using about 12% of maxheap.
Here’s the explanation for the reported behavior:
As the various background PRPC agents and daemons run, it uses memory and the used heap will be queued for finalization (automatically by java).
Since the heap size is set large (to accommodate the expected user load) - gc will not occur until the heap reaches the gc threshold - so monitoring tools may notice the increasing heap size.
The act of taking a heap dump (which is using as a tool to inspect the large heap) will trigger a gc - and the resulting heap dump shows a much smaller heap (approximate 12% of max) with no apparent leaks.
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