WaitUntilIdle optimize idling time (#10878)

Relates to @bboreham optimization in https://github.com/prometheus/prometheus/pull/10859

Bryan did reduce the sleep time improving the deltas on the benchmark by
quite a lot. However I've been working on a similar implementation for
out of order and I noticed that we actually get into this method
thousands of times.

@ywwg had the brilliant idea of not always sleeping before the select
but actually make it a case in the select so we only sleep if we need
to.

The benchmark deltas are amazing

```
❯ benchstat old_implementation.txt new_implementation_using_time_after.txt
name                                                                                                     old time/op  new time/op  delta
LoadWAL/batches=10,seriesPerBatch=100,samplesPerSeries=7200,exemplarsPerSeries=0,mmappedChunkT=0-8        521ms ±25%   253ms ± 6%  -51.47%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=100,samplesPerSeries=7200,exemplarsPerSeries=36,mmappedChunkT=0-8       773ms ± 3%   369ms ±31%  -52.23%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=100,samplesPerSeries=7200,exemplarsPerSeries=72,mmappedChunkT=0-8       592ms ±28%   297ms ±28%  -49.80%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=100,samplesPerSeries=7200,exemplarsPerSeries=360,mmappedChunkT=0-8      547ms ± 2%  999ms ±187%     ~     (p=0.690 n=5+5)
LoadWAL/batches=10,seriesPerBatch=10000,samplesPerSeries=50,exemplarsPerSeries=0,mmappedChunkT=0-8        11.3s ± 4%    1.3s ±44%  -88.48%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=10000,samplesPerSeries=50,exemplarsPerSeries=2,mmappedChunkT=0-8        11.1s ± 1%    1.2s ±20%  -89.08%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=0,mmappedChunkT=0-8        1.24s ± 3%   0.18s ± 7%  -85.76%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=2,mmappedChunkT=0-8        1.24s ± 2%   0.18s ± 5%  -85.24%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=5,mmappedChunkT=0-8        1.23s ± 5%   0.27s ±33%  -77.73%  (p=0.008 n=5+5)
LoadWAL/batches=10,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=24,mmappedChunkT=0-8       1.28s ± 1%   0.36s ± 7%  -71.51%  (p=0.008 n=5+5)
LoadWAL/batches=100,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=0,mmappedChunkT=3800-8    12.1s ± 1%    3.1s ± 6%  -74.33%  (p=0.008 n=5+5)
LoadWAL/batches=100,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=2,mmappedChunkT=3800-8    12.1s ± 1%    3.4s ± 4%  -71.94%  (p=0.008 n=5+5)
LoadWAL/batches=100,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=5,mmappedChunkT=3800-8    12.1s ± 1%    3.8s ±17%  -68.35%  (p=0.008 n=5+5)
LoadWAL/batches=100,seriesPerBatch=1000,samplesPerSeries=480,exemplarsPerSeries=24,mmappedChunkT=3800-8   12.4s ± 1%    4.0s ±18%  -67.71%  (p=0.008 n=5+5)
```

Benchmarked on Linux
```
goos: linux
goarch: amd64
pkg: github.com/prometheus/prometheus/tsdb
cpu: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
```

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>
This commit is contained in:
Jesus Vazquez 2022-06-30 15:00:04 +02:00 committed by GitHub
parent db2614102f
commit 6cfe44d7fd
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View file

@ -438,10 +438,9 @@ func (wp *walSubsetProcessor) waitUntilIdle() {
} }
wp.input <- []record.RefSample{} wp.input <- []record.RefSample{}
for len(wp.input) != 0 { for len(wp.input) != 0 {
time.Sleep(10 * time.Microsecond)
select { select {
case <-wp.output: // Allow output side to drain to avoid deadlock. case <-wp.output: // Allow output side to drain to avoid deadlock.
default: case <-time.After(10 * time.Microsecond):
} }
} }
} }