Track evictions in the PostingsForMatchers cache #824
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Signed-off-by: Marco Pracucci <[email protected]>
Signed-off-by: Marco Pracucci <[email protected]>
charleskorn
approved these changes
Jan 28, 2025
tsdb/postings_for_matchers_cache.go
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| if evictionReasons[evictionReasonTTL] > 0 { | ||
| c.metrics.evictionsBecauseTTL.Add(float64(evictionReasons[evictionReasonTTL])) | ||
| } | ||
| if evictionReasons[evictionReasonMaxBytes] > 0 { | ||
| c.metrics.evictionsBecauseMaxBytes.Add(float64(evictionReasons[evictionReasonMaxBytes])) | ||
| } | ||
| if evictionReasons[evictionReasonMaxItems] > 0 { | ||
| c.metrics.evictionsBecauseMaxItems.Add(float64(evictionReasons[evictionReasonMaxItems])) | ||
| } | ||
| if evictionReasons[evictionReasonUnknown] > 0 { | ||
| c.metrics.evictionsBecauseUnknown.Add(float64(evictionReasons[evictionReasonUnknown])) | ||
| } |
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Are the ifs here necessary? If so, would be good to add a comment explaining why.
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I thought it was slightly after on high eviction rate (assuming most of the times cached promises are removed because of 1 out of 4 reasons), but benchmark doesn't show it far, so I've removed the if stataements.
goos: darwin
goarch: arm64
pkg: github.com/prometheus/prometheus/tsdb
cpu: Apple M3 Pro
│ before.txt │ after.txt │
│ sec/op │ sec/op vs base │
PostingsForMatchersCache/no_evictions-11 640.7n ± 3% 644.4n ± 9% ~ (p=0.260 n=6)
PostingsForMatchersCache/high_eviction_rate-11 10.75µ ± 0% 10.73µ ± 0% ~ (p=0.260 n=6)
PostingsForMatchersCache_ConcurrencyOnHighEvictionRate-11 338.6n ± 4% 332.5n ± 3% ~ (p=0.818 n=6)
geomean 1.326µ 1.320µ -0.45%
│ before.txt │ after.txt │
│ B/op │ B/op vs base │
PostingsForMatchersCache/no_evictions-11 974.0 ± 0% 974.0 ± 0% ~ (p=1.000 n=6) ¹
PostingsForMatchersCache/high_eviction_rate-11 26.32Ki ± 0% 26.32Ki ± 0% ~ (p=1.000 n=6) ¹
PostingsForMatchersCache_ConcurrencyOnHighEvictionRate-11 1.003Ki ± 1% 1.000Ki ± 1% ~ (p=0.571 n=6)
geomean 2.928Ki 2.926Ki -0.08%
¹ all samples are equal
│ before.txt │ after.txt │
│ allocs/op │ allocs/op vs base │
PostingsForMatchersCache/no_evictions-11 20.00 ± 0% 20.00 ± 0% ~ (p=1.000 n=6) ¹
PostingsForMatchersCache/high_eviction_rate-11 46.00 ± 0% 46.00 ± 0% ~ (p=1.000 n=6) ¹
PostingsForMatchersCache_ConcurrencyOnHighEvictionRate-11 21.00 ± 5% 20.00 ± 5% ~ (p=0.567 n=6)
geomean 26.83 26.40 -1.61%
¹ all samples are equal
Signed-off-by: Marco Pracucci <[email protected]>
pracucci
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track-postings-for-matchers-cache-eviction-metrics
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In #822 I've introduced metrics for the
PostingsForMatcherscache. In this PR I'm extending the metrics to count evictions by reason.Ref: https://github.com/grafana/pir-actions/issues/307
Benchmarks