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Optimize zap.Any to allocate less mamory on stack
This is an alternative to #1301 and #1302. It's not as fast as these two options, but it still gives us half the stack reduction without the `unsafe` usage. Interestingly it seems that on both arm64 and amd64 the new code, with the closure, is faster than the plain old switch. We do see a ~5-10ns delay on `Any` creation if it's used without `logger`, but that's minimal and not realistic. Bunch of credit for this goes to @cdvr1993, we started independently, I was about to give up but the conversations pushed me forward. In the end he ended up going into a more advanced land where I dare not to enter. Longer version: We have identified an issue where zap.Any can cause performance degradation due to stack size. This is apparently cased by the compiler assigning 4.8kb (a zap.Field per arm of the switch statement) for zap.Any on stack. This can result in an unnecessary runtime.newstack+runtime.copystack. A github issue against Go language is pending. This can be particularly bad if `zap.Any` was to be used in a new goroutine, since the default goroutine sizes can be as low as 2kb (it can vary depending on average stack size - see golang/go#18138). This is an alternative to #1301, @cdvr and me were talking about this, and he inspired this idea with the closure. By using a function and a closure we're able to reduce the size and remove the degradation. At least on my laptop, this change result in a new performance gain, as all benchmarks show reduced time. 10 runs. ``` ❯ benchstat ~/before2.txt ~/after2.txt goos: darwin goarch: arm64 pkg: go.uber.org/zap │ /Users/pawel/before2.txt │ /Users/pawel/after2.txt │ │ sec/op │ sec/op vs base │ Any/str-no-logger-12 3.344n ± 1% 3.029n ± 1% -9.40% (p=0.000 n=10) Any/any-no-logger-12 13.80n ± 4% 18.67n ± 1% +35.29% (p=0.000 n=10) Any/str-with-logger-12 372.4n ± 3% 363.6n ± 1% -2.35% (p=0.001 n=10) Any/any-with-logger-12 369.2n ± 1% 363.6n ± 1% -1.52% (p=0.002 n=10) Any/str-in-go-12 587.2n ± 2% 587.0n ± 1% ~ (p=0.617 n=10) Any/any-in-go-12 666.5n ± 3% 567.6n ± 1% -14.85% (p=0.000 n=10) Any/str-in-go-with-stack-12 448.6n ± 18% 403.4n ± 13% ~ (p=0.280 n=10) Any/any-in-go-with-stack-12 564.9n ± 7% 443.2n ± 4% -21.55% (p=0.000 n=10) geomean 167.8n 160.7n -4.23% │ /Users/pawel/before2.txt │ /Users/pawel/after2.txt │ │ B/op │ B/op vs base │ Any/str-no-logger-12 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹ Any/any-no-logger-12 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹ Any/str-with-logger-12 64.00 ± 0% 64.00 ± 0% ~ (p=1.000 n=10) ¹ Any/any-with-logger-12 64.00 ± 0% 64.00 ± 0% ~ (p=1.000 n=10) ¹ Any/str-in-go-12 88.00 ± 0% 88.00 ± 0% ~ (p=1.000 n=10) ¹ Any/any-in-go-12 88.00 ± 0% 88.00 ± 0% ~ (p=1.000 n=10) ¹ Any/str-in-go-with-stack-12 88.00 ± 0% 88.00 ± 0% ~ (p=1.000 n=10) ¹ Any/any-in-go-with-stack-12 88.00 ± 0% 88.00 ± 0% ~ (p=1.000 n=10) ¹ geomean ² +0.00% ² ¹ all samples are equal ² summaries must be >0 to compute geomean │ /Users/pawel/before2.txt │ /Users/pawel/after2.txt │ │ allocs/op │ allocs/op vs base │ Any/str-no-logger-12 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹ Any/any-no-logger-12 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹ Any/str-with-logger-12 1.000 ± 0% 1.000 ± 0% ~ (p=1.000 n=10) ¹ Any/any-with-logger-12 1.000 ± 0% 1.000 ± 0% ~ (p=1.000 n=10) ¹ Any/str-in-go-12 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Any/any-in-go-12 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Any/str-in-go-with-stack-12 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Any/any-in-go-with-stack-12 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ geomean ``` On absolute terms: Before, on arm64: ``` goos: darwin goarch: arm64 pkg: go.uber.org/zap BenchmarkAny/str-with-logger 3154850 387.9 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-2 3239221 371.0 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-4 3273285 363.8 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-8 3251991 372.4 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger 2944020 401.1 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-2 2984863 368.2 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-4 3265248 363.0 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-8 3301592 365.9 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-in-go 764239 1423 ns/op 140 B/op 2 allocs/op BenchmarkAny/str-in-go-2 1510189 753.0 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-4 3013986 369.1 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-8 2128927 540.0 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go 464083 2551 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-2 818104 1347 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-4 1587925 698.9 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-8 2452558 466.7 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack 767626 1440 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-2 1534382 771.1 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-4 2384058 433.4 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-8 3146942 450.0 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack 434194 2524 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-2 851312 1304 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-4 1570944 710.1 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-8 2546115 604.6 ns/op 88 B/op 2 allocs/op PASS ok go.uber.org/zap 50.238s ``` After: ``` goos: darwin goarch: arm64 pkg: go.uber.org/zap BenchmarkAny/str-with-logger 3191725 382.2 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-2 3159882 367.4 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-4 2998960 373.0 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-8 3264657 361.7 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger 3168627 386.2 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-2 3169394 364.4 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-4 3271981 368.9 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-8 3293463 362.5 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-in-go 793905 1388 ns/op 143 B/op 2 allocs/op BenchmarkAny/str-in-go-2 1724048 748.4 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-4 2536380 444.9 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-8 2177941 586.1 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go 890155 1237 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-2 1836302 719.1 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-4 3671503 322.2 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-8 2257405 540.8 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack 811408 1457 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-2 1384990 729.6 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-4 3228151 381.8 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-8 2678596 450.8 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack 821092 1386 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-2 1747638 662.3 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-4 3747934 341.9 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-8 2678191 463.6 ns/op 88 B/op 2 allocs/op PASS ok go.uber.org/zap 53.238s ``` And amd64, before: ``` % go test -bench BenchmarkAny -benchmem -run errs -cpu 1,2,4,8 goos: linux goarch: amd64 pkg: go.uber.org/zap cpu: AMD EPYC 7B13 BenchmarkAny/str-no-logger 100000000 11.58 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-no-logger-2 100000000 11.52 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-no-logger-4 100000000 11.56 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-no-logger-8 100000000 11.50 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger 39399811 30.35 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger-2 39448304 30.63 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger-4 39647024 30.32 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger-8 39479619 30.46 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-with-logger 1798702 669.3 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-2 1862551 647.1 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-4 1848636 642.2 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-8 1878465 656.7 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger 1776140 684.3 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-2 1868102 668.5 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-4 1869589 639.9 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-8 1782540 648.5 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-in-go 458112 2594 ns/op 91 B/op 2 allocs/op BenchmarkAny/str-in-go-2 820398 1344 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-4 1392148 969.6 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-8 1790403 644.8 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go 220327 4897 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-2 494391 2701 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-4 823672 1399 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-8 1591206 746.8 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack 384094 2820 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-2 809073 1530 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-4 1464598 933.0 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-8 1943251 578.0 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack 233019 4967 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-2 356689 2848 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-4 791342 1385 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-8 1662126 746.0 ns/op 88 B/op 2 allocs/op PASS ok go.uber.org/zap 51.671s ``` After: ``` goos: linux goarch: amd64 pkg: go.uber.org/zap cpu: AMD EPYC 7B13 BenchmarkAny/str-no-logger 100000000 11.65 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-no-logger-2 100000000 11.64 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-no-logger-4 100000000 11.63 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-no-logger-8 100000000 11.65 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger 27779637 44.20 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger-2 27881986 42.96 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger-4 27587953 43.39 ns/op 0 B/op 0 allocs/op BenchmarkAny/any-no-logger-8 26861058 43.43 ns/op 0 B/op 0 allocs/op BenchmarkAny/str-with-logger 1749990 690.4 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-2 1807341 660.3 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-4 1821039 654.3 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-with-logger-8 1865083 650.8 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger 1677643 741.3 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-2 1905400 689.4 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-4 1843364 646.2 ns/op 64 B/op 1 allocs/op BenchmarkAny/any-with-logger-8 1899883 645.8 ns/op 64 B/op 1 allocs/op BenchmarkAny/str-in-go 453326 2479 ns/op 92 B/op 2 allocs/op BenchmarkAny/str-in-go-2 724555 1580 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-4 1358790 953.3 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-8 1805985 585.6 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go 466447 2395 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-2 874053 1487 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-4 1457768 834.7 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-8 1795317 632.5 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack 407620 2749 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-2 725614 1597 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-4 1303908 863.7 ns/op 88 B/op 2 allocs/op BenchmarkAny/str-in-go-with-stack-8 1957864 609.1 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack 497640 2401 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-2 648355 1549 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-4 1486416 869.9 ns/op 88 B/op 2 allocs/op BenchmarkAny/any-in-go-with-stack-8 2116040 568.8 ns/op 88 B/op 2 allocs/op PASS ```
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