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| author | Meir Fischer <meirfischer@gmail.com> | 2017-06-25 21:17:52 -0400 |
|---|---|---|
| committer | Brad Fitzpatrick <bradfitz@golang.org> | 2017-06-28 20:47:26 +0000 |
| commit | 3858349ec956b4abb052ba3191da16dc487c4ad4 (patch) | |
| tree | b8301c51cfc7ecc7581d20ee01d535cf207a33ed /src/testing | |
| parent | 32002079083e533e11209824bd9e3a797169d1c4 (diff) | |
| download | go-3858349ec956b4abb052ba3191da16dc487c4ad4.tar.xz | |
testing: always ReadMemStats before first benchmark run
If the only way the user indicates they want alloc stats shown
is via ReportAllocs, we don't know that until benchFunc is run.
Therefore, StopTimer's ReadMemStats will return incorrect data
for single cycle runs since there's no counterpart ReadMemStats from
StartTimer that initializes alloc stats.
It appears that this bug was introduced by CL 46612,
"testing: only call ReadMemStats if necessary when benchmarking"
Fixes #20590
Change-Id: I3b5ef91677823f4b98011880a3be15423baf7e33
Reviewed-on: https://go-review.googlesource.com/46612
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src/testing')
| -rw-r--r-- | src/testing/benchmark.go | 8 | ||||
| -rw-r--r-- | src/testing/sub_test.go | 10 |
2 files changed, 13 insertions, 5 deletions
diff --git a/src/testing/benchmark.go b/src/testing/benchmark.go index 8b7f5cebaf..be9e96d50c 100644 --- a/src/testing/benchmark.go +++ b/src/testing/benchmark.go @@ -73,11 +73,9 @@ type B struct { // a call to StopTimer. func (b *B) StartTimer() { if !b.timerOn { - if *benchmarkMemory || b.showAllocResult { - runtime.ReadMemStats(&memStats) - b.startAllocs = memStats.Mallocs - b.startBytes = memStats.TotalAlloc - } + runtime.ReadMemStats(&memStats) + b.startAllocs = memStats.Mallocs + b.startBytes = memStats.TotalAlloc b.start = time.Now() b.timerOn = true } diff --git a/src/testing/sub_test.go b/src/testing/sub_test.go index af2d39c5be..acf5dea878 100644 --- a/src/testing/sub_test.go +++ b/src/testing/sub_test.go @@ -540,6 +540,16 @@ func TestBenchmarkStartsFrom1(t *T) { }) } +func TestBenchmarkReadMemStatsBeforeFirstRun(t *T) { + var first = true + Benchmark(func(b *B) { + if first && (b.startAllocs == 0 || b.startBytes == 0) { + panic(fmt.Sprintf("ReadMemStats not called before first run")) + } + first = false + }) +} + func TestParallelSub(t *T) { c := make(chan int) block := make(chan int) |