.NET Trending-Leak-Analysis Memory Snapshot setting causes long suspension times
We've been struggling with DynaTrace reporting long "suspension" times during our performance tests for the last few weeks, and wanted to share with the DT community what the resolution was.
This was severally impacting our performance test results, and the team spent countless hours using memory analysis to try to determine the root cause. Several other memory analysis tools (like PerfView) showed GC times to be <2 seconds each, but DynaTrace was showing suspension times of 25+ seconds.
In the end, we determined this was caused by the ".NET Trending/Leak-Analysis Memory Snapshot" option set to Always On. (System Profile -> Agent Group -> Agent Mapping -> Advanced). After changing that setting to Automatic, performance was incredibly better.
So the "suspension" time reported by DT is not just .Net GC, but it could also be DT itself doing memory analysis.
Hi Andrew
Thanks for sharing this.
The impact of this setting is actually documented and also in the UI where you have to enable this setting (off by default) it says that this causes runtime overhead. The reason for the overhead can be found in Microsoft CLR - we have reported this problem to Microsoft but it hasnt been addressed yet. Therefore we have this option turned-off by default and suggest to only turn it on in case you need to create Memory Dumps for Memory Leak Analysis.
Again - thanks for sharing!!
Andi
