9a5574afe6
First, we know that Go source files almost always weigh at least a few kilobytes, so we can kickstart the output buffer to be a reasonable size and reduce the initial number of incremental allocations and copies when appending bytes or strings to output. Second, in nodeSize we use a nested printer, but we don't actually need its printed bytes - we only need to know how many bytes it prints. For that reason, use a throwaway buffer: the part of our output buffer between length and capacity, as we haven't used it yet. Third, use a sync.Pool to reuse allocated printers. The current API doesn't allow reusing printers, and some programs like gofmt will print many files in sequence. Those changes combined result in a modest reduction in allocations and CPU usage. The benchmark uses testdata/parser.go, which has just over two thousand lines of code, which is pretty standard size-wise. We also split the Print benchmark to cover both a medium-sized ast.File as well as a pretty small ast.Decl node. The latter is a somewhat common scenario in gopls, which has code actions which alter small bits of the AST and print them back out to rewrite only a few lines in a file. name old time/op new time/op delta PrintFile-16 5.43ms ± 1% 4.85ms ± 3% -10.68% (p=0.000 n=9+10) PrintDecl-16 19.1µs ± 0% 18.5µs ± 1% -3.04% (p=0.000 n=10+10) name old speed new speed delta PrintFile-16 9.56MB/s ± 1% 10.69MB/s ± 3% +11.81% (p=0.000 n=8+10) PrintDecl-16 1.67MB/s ± 0% 1.73MB/s ± 1% +3.05% (p=0.000 n=10+10) name old alloc/op new alloc/op delta PrintFile-16 332kB ± 0% 107kB ± 2% -67.87% (p=0.000 n=10+10) PrintDecl-16 3.92kB ± 0% 3.28kB ± 0% -16.38% (p=0.000 n=10+10) name old allocs/op new allocs/op delta PrintFile-16 3.45k ± 0% 2.42k ± 0% -29.90% (p=0.000 n=10+10) PrintDecl-16 56.0 ± 0% 46.0 ± 0% -17.86% (p=0.000 n=10+10) Change-Id: I475a3babca77532b2d51888f49710f74763d81d2 Reviewed-on: https://go-review.googlesource.com/c/go/+/424924 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Alan Donovan <adonovan@google.com> |
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The Go Programming Language
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