Achille Roussel ba7b8ca336 iter: reduce memory footprint of iter.Pull functions ... The implementation of iter.Pull and iter.Pull2 functions is based on closures and sharing local state, which results in one heap allocation for each captured variable. The number of heap allocations can be reduced by grouping the state shared between closures in a struct, allowing the compiler to allocate all local variables in a single heap region instead of creating individual heap objects for each variable. This approach can sometimes have downsides when it couples unrelated objects in a single memory region, preventing the garbage collector from reclaiming unused memory. While technically only a subset of the local state is shared between the next and stop functions, it seems unlikely that retaining the rest of the state until stop is reclaimed would be problematic in practice, since the two closures would often have very similar lifetimes. The change also reduces the total memory footprint due to alignment rules, the two booleans can be packed in memory and sometimes can even exist within the padding space of the v value. There is also less metadata needed for the garbage collector to track each individual heap allocation. goos: darwin goarch: arm64 pkg: iter cpu: Apple M2 Pro │ /tmp/bench.old │ /tmp/bench.new │ │ sec/op │ sec/op vs base │ Pull-12 218.6n ± 7% 146.1n ± 0% -33.19% (p=0.000 n=10) Pull2-12 239.8n ± 5% 155.0n ± 5% -35.36% (p=0.000 n=10) geomean 229.0n 150.5n -34.28% │ /tmp/bench.old │ /tmp/bench.new │ │ B/op │ B/op vs base │ Pull-12 288.0 ± 0% 176.0 ± 0% -38.89% (p=0.000 n=10) Pull2-12 312.0 ± 0% 176.0 ± 0% -43.59% (p=0.000 n=10) geomean 299.8 176.0 -41.29% │ /tmp/bench.old │ /tmp/bench.new │ │ allocs/op │ allocs/op vs base │ Pull-12 11.000 ± 0% 5.000 ± 0% -54.55% (p=0.000 n=10) Pull2-12 12.000 ± 0% 5.000 ± 0% -58.33% (p=0.000 n=10) geomean 11.49 5.000 -56.48% Change-Id: Iccbe233e8ae11066087ffa4781b66489d0d410a7 Reviewed-on: https://go-review.googlesource.com/c/go/+/552375 Reviewed-by: Sean Liao <sean@liao.dev> Auto-Submit: Sean Liao <sean@liao.dev> Reviewed-by: qiu laidongfeng2 <2645477756@qq.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>		2025-04-14 15:10:49 -07:00
..
iter.go	…
pull_test.go	…