Tuesday, June 17, 2008

Get thread dumps during supplemental load tests

I recently found a bug in an application that the developers were not aware of. The code had a synchronized block they thought would be low cost. Low and behold in our load testing we found that after a certain number of users were active their response times started to go up exponentially. I took some thread dumps and found the synchronized block of code.

For anyone interested in performance:

1. Load test
2. Get thread dumps during bad response times.

If neither is done there will be problems in production. If you do not know how to analyze javacores open a PMR with IBM and IBM Support can help identify the problem.

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