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From "Internal Jenkins (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-4187: Switch RPC latency metrics to histograms
Date Mon, 26 Sep 2016 22:07:17 GMT
Internal Jenkins has submitted this change and it was merged.

Change subject: IMPALA-4187: Switch RPC latency metrics to histograms

IMPALA-4187: Switch RPC latency metrics to histograms

It's usually better to measure latency distributions with histograms,
not avg / min / max. This change switches out the metrics that measure
the latency of RPC processing time to histograms.

Add HistogramMetric::Reset() to allow histogram to remove all
entries. Added spinlock around histogram access.

On a 8-core i7 @ 3.4GHz, the following throughputs were observed:

1 thread -> 25M updates/sec
4 threads -> 7M updates/sec
16 threads -> 5M updates/sec

Each histogram takes ~108KB of storage for its buckets. This can be
reduced by reducing the maximum value, currently 60 minutes.

The new metrics have the following text representation:

Count: 148, 25th %-ile: 0, 50th %-ile: 0, 75th %-ile: 0, 90th %-ile: 0,
95th %-ile: 0, 99.9th %-ile: 1ms

Which changes from the old:

count: 345, last: 6ms, min: 0, max: 12ms, mean: 1ms, stddev: 1ms

Change-Id: I9ba6d4270dd5676eeeff35ad8d9dc5dcddd95e34
Reviewed-by: Henry Robinson <>
Tested-by: Internal Jenkins
M be/src/rpc/
M be/src/rpc/rpc-trace.h
M be/src/util/histogram-metric.h
M common/thrift/metrics.json
4 files changed, 64 insertions(+), 37 deletions(-)

  Henry Robinson: Looks good to me, approved
  Internal Jenkins: Verified

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Gerrit-MessageType: merged
Gerrit-Change-Id: I9ba6d4270dd5676eeeff35ad8d9dc5dcddd95e34
Gerrit-PatchSet: 5
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Henry Robinson <>
Gerrit-Reviewer: Dan Hecht <>
Gerrit-Reviewer: Henry Robinson <>
Gerrit-Reviewer: Internal Jenkins
Gerrit-Reviewer: Juan Yu <>
Gerrit-Reviewer: Matthew Jacobs <>
Gerrit-Reviewer: Sailesh Mukil <>

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