go-gcstats
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aclements
Go runtime GC trace analysis and statistics tool
This repository provides tools for computing statistics and creating plots from garbage collection traces produced by the Go 1.4 and 1.5 runtimes. To collect such a trace, run a Go program with
$ env GODEBUG=gctrace=1 <program>
The garbage collection trace will be written to stderr.
plot-gctrace
cmd/plot-gctrace plots the breakdown of GC CPU utilization and heap
size versus wall-clock time. plot-gctrace is a Python script, so it
can be executed directly.
gcstats
cmd/gcstats computes and plots a variety of high-level statistics
from a GC trace. To install it, run
$ go get github.com/aclements/go-gcstats/cmd/gcstats
By default, gcstats prints a high-level summary of the pause time
distribution and the mutator utilization,
$ gcstats < gctrace
Pause times: max=1ms 99%ile=1ms 95%ile=929us mean=399us
Mean mutator utilization: 89%
10ms mutator utilization: min=51% 1%ile=55% 5%ile=55%
It can also plot the pause time distribution as a kernel density estimate or empirical CDF:
$ gcstats -stopcdf -show < gctrace
However, the pause time distribution doesn't show you how close
together the pauses are (all pauses could be under a millisecond, but
if they're only a microsecond apart, that's still bad!). Hence,
gcstats can also plot a mutator utilization topology, which shows
mutator utilization at various percentiles and over windows of time
ranging from 1ms to 1s.
$ gcstats -mut -show < gctrace
Go 1.4
Note that some of the analyses require a small patch to the Go 1.4 runtime to add program execution times. To apply this patch to a Go 1.4 tree, run
$ cd $GOROOT
$ patch < $GOPATH/src/github.com/aclements/go-gcstats/go14.patch
Dependencies for plotting
The plotting facilities of these tools currently depend on Python 3 and matplotlib. In addition, Seaborn is recommended.
To install these packages on Debian and Ubuntu, use
apt-get install python3-matplotlib python3-scipy python3-pandas
pip3 install seaborn
For general instructions on installing Seaborn, see installing Seaborn.
aclements