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Posted to commits@druid.apache.org by GitBox <gi...@apache.org> on 2021/05/18 22:44:42 UTC
[GitHub] [druid] jasonk000 commented on issue #11140: Druid Router UI throwing 504 when there are too many tasks
jasonk000 commented on issue #11140:
URL: https://github.com/apache/druid/issues/11140#issuecomment-843615701
I have done some profiling on our stack here, my analysis follows. We are configured with `HeapMemoryTaskStorage`.
By issuing repeated SQL requests against broker (such as with `ab`) we can see the workload increase on `overlord`. Taking a CPU profile of the overlord host and focusing on the CPU related to the `/tasks` endpoint gives a view that over 50% of the CPU load is in `HeapMemoryTaskStorage::getTasks`, and only a small % of time in serialization.
Notice specifically in the before/after below that the % of time (width of bar) of `getCompletedTaskInfo...` (highlighted in a magenta-ish colour), and that the bulk of the time is in `sortedCopy`.
Before
After changes, `getCompletedTaskInfo...` is significantly reduced as a % of the overall CPU time, so much that serialization is now far larger than the query time.
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