Francisco Chicharro created SLING-3277:
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Summary: RequestProcessorMBeanImpl.resetStatistics does not reset
sum and squared sum variable values
Key: SLING-3277
URL: https://issues.apache.org/jira/browse/SLING-3277
Project: Sling
Issue Type: Bug
Components: Engine
Affects Versions: Engine 2.2.10
Reporter: Francisco Chicharro
Priority: Minor
The RequestProcessorMBeanImpl uses the variables: durationMsecSumX and
durationMsecSumX2 to store the sum and squared sum of request durations. These
variables are used later to calculate the statistics MeanRequestDurationMsec
and StandardDeviationDurationMsec.
To calculate these statistics it uses the mentioned sum and sumX2 variables and
the number of requests processed.
The issue arises when the resetStatistics method is invoked: it resets the
number of processed requests to 0, but not the sum and squared sum variables.
For instance, if you have an accumulated processing time of 10000 msecs and 100
requests, the MeanRequestDurationMsec will be 100 msecs, which is correct.
If you invoke resetStatistics method at that time, the number of request will
be reset to 0 while the sum of request durations will keep being 10000 msecs.
If next request is processed in 10msecs you will have accumulated a sum of
request durations of 10010 msecs and only one request. So the
MeanRequestDurationMsec statistic will display 10010msecs, which is wrong.
The same issue occurs with the statistics for ServletCallCount and
PeakRecursionDepth.
To solve this issue the following variables need to be reset (set to 0) in the
resetStatistics method:
- durationMsecSumX
- durationMsecSumX2
- servletCallCountSumX
- servletCallCountSumX2
- peakRecursionDepthSumX
- peakRecursionDepthSumX2
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