Details
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Improvement
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Status: Resolved
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Minor
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Resolution: Fixed
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3.4.7, 3.4.9
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None
Description
I posted a thread on the mailing list about finding AvgRequestLatency metric to be 0 all the time. I believe this is a valuable metric because it is useful to baseline performance of ZK and know when something is going wrong.
Another user (Arshad Mohammad) wrote up these notes. I am not a developer so i do not have ability to patch this. Filing this so hopefully someone with developer abilities can add this improvement.
"I find two reason whys AvgRequestLatency is almost all the time 0
1) Ping requests are counted the most:
AvgRequestLatency is calculated as
AvgRequestLatency=totalLatency/count
Ping requests come very often and complete very fast, these request add
nothing to totalLatency but add one to count.
2) Wrong data type is chosen to store AvgRequestLatency:
AvgRequestLatency is calculated and store as the long value instead of
double vlaue.
In my opinion ZooKeeper code should be modified to improve this metrics
i) Ping request should be ignored while recording the statistics or at
least should be configurable whether to ignore or not. If ping request is
not counted even other metrics will be more meaningful.
ii) AvgRequestLatency should be of double type"
