Skip to main content

This content has been archived and is no longer being updated. Links may not function; however, this content may be relevant to outdated versions of the product.

Support Article

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%.

Error Messages

Heap size threshold increased and it is more than 90%

Steps to Reproduce

Not applicable

Root Cause

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.

Published November 2, 2016 - Updated October 8, 2020

Was this useful?

0% found this useful

Have a question? Get answers now.

Visit the Collaboration Center to ask questions, engage in discussions, share ideas, and help others.

Did you find this content helpful?

Want to help us improve this content?

We'd prefer it if you saw us at our best.

Pega Community has detected you are using a browser which may prevent you from experiencing the site as intended. To improve your experience, please update your browser.

Close Deprecation Notice
Contact us