Don't use zeropool for postings cache key building #4869
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Zeropool is useful when we can't retain the pointer to put it back into
the pool, but when we can it causes an unnecessary overhead of a second
pool.
This saves some nanoseconds, without an allocations change
goos: linux
goarch: amd64
pkg: github.com/grafana/mimir/pkg/storegateway/indexcache
cpu: 11th Gen Intel(R) Core(TM) i7-11700K @ 3.60GHz
│ main.txt │ new.txt │
│ sec/op │ sec/op vs base │
StringCacheKeys/postings-16 1.011µ ± 0% 1.001µ ± 3% -0.94% (p=0.033 n=10)
StringCacheKeys/series_ref-16 133.9n ± 13% 120.5n ± 9% -9.97% (p=0.000 n=10)
StringCacheKeys/expanded_postings-16 418.0n ± 7% 328.2n ± 21% -21.47% (p=0.000 n=10)
geomean 383.8n 340.8n -11.20%
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
pracucci
approved these changes
Apr 28, 2023
| @@ -32,10 +32,10 @@ const ( | |||
| ) | |||
|
|
|||
| var ( | |||
| postingsCacheKeyLabelHashBufferPool = zeropool.New[[]byte](func() []byte { | |||
| // We assume the label name/value pair is typically not longer than 1KB. | |||
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Didn't you like my comment? :D
There was a problem hiding this comment.
Oh, I initially changed to return new([]byte) and allocate a max(expectedLen, 1024) in the usage, but that seemed unnecessary complex to me, so I lost the comment when I switched back. Recovered it now :)
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
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What this PR does
Late feedback on #4861, so I decided to open a PR instead of commenting.
Zeropool is useful when we can't retain the pointer to put it back into the pool, but when we can it causes an unnecessary overhead of a second pool.
This saves some nanoseconds, without an allocations change
Which issue(s) this PR fixes or relates to
None, followup on #4861
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]