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Megmeehey avatar image
Megmeehey asked Erick Ramirez answered

Does enabling probabilistic tracing stop some internal work?

Hi!

Does enabling probabilistic tracing in Cassandra (3.11.2) stops some internal work?

Whenever I execute `nodetool settraceprobability 0.01` CPU usage on that node (as well as requests latency on the whole cluster) goes down.
When I set 0 probability back, it goes up.

Here is the CPU usage graph:
22.jpg
performance
22.jpg (55.1 KiB)
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1 Answer

Erick Ramirez avatar image
Erick Ramirez answered

Tracing does not prevent tasks from operating but since tracing is a very expensive operation, it can significantly impact the performance of your cluster.

Depending on how busy your cluster is, exercise a lot of caution when enabling probabilistic tracing. Only enable it on one node at a time and start with a very low value, say 0.1% (probability value of 0.001).

Monitor the performance of the node for at least 5-10 minutes. Only increase the probability in very small increments if absolutely necessary.

If you see any negative effects, disable tracing immediately. We recommend that you don't leave tracing on unless you are actively monitoring the performance of your cluster. Cheers!

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