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runtime,runtime/metrics: add metric for distribution of GC pauses

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For #37112.

Change-Id: Ibb0425c9c582ae3da3b2662d5bbe830d7df9079c
Reviewed-on: https://go-review.googlesource.com/c/go/+/247047
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
This commit is contained in:
Michael Anthony Knyszek 2020-08-06 21:59:13 +00:00 • committed by Michael Knyszek
parent 36c5edd8d9
commit d39a89fd58
6 changed files with 54 additions and 0 deletions
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22
src/runtime/metrics_test.go
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@ -90,6 +90,11 @@ func TestReadMetricsConsistency(t *testing.T) {
// things (e.g. allocating) so what we read can't reasonably compared
// to runtime values.
// Run a few GC cycles to get some of the stats to be non-zero.
runtime.GC()
runtime.GC()
runtime.GC()
// Read all the supported metrics through the metrics package.
descs, samples := prepareAllMetricsSamples()
metrics.Read(samples)
@ -102,6 +107,10 @@ func TestReadMetricsConsistency(t *testing.T) {
alloc, free *metrics.Float64Histogram
total uint64
}
var gc struct {
numGC uint64
pauses uint64
}
for i := range samples {
kind := samples[i].Value.Kind()
if want := descs[samples[i].Name].Kind; kind != want {
@ -128,6 +137,14 @@ func TestReadMetricsConsistency(t *testing.T) {
objects.alloc = samples[i].Value.Float64Histogram()
case "/gc/heap/frees-by-size:objects":
objects.free = samples[i].Value.Float64Histogram()
case "/gc/cycles:gc-cycles":
gc.numGC = samples[i].Value.Uint64()
case "/gc/pauses:seconds":
h := samples[i].Value.Float64Histogram()
gc.pauses = 0
for i := range h.Counts {
gc.pauses += h.Counts[i]
}
}
}
if totalVirtual.got != totalVirtual.want {
@ -159,6 +176,11 @@ func TestReadMetricsConsistency(t *testing.T) {
}
}
}
// The current GC has at least 2 pauses per GC.
// Check to see if that value makes sense.
if gc.pauses < gc.numGC*2 {
t.Errorf("fewer pauses than expected: got %d, want at least %d", gc.pauses, gc.numGC*2)
}
}
func BenchmarkReadMetricsLatency(b *testing.B) {