96caea4103
Previously we would spin up a new goroutine for every directory we needed to parse. Since parent directories cannot exit until children have exited, in large GOPATH directories we could have 8000+ goroutines evaluating directories concurrently. The race detector uses tsan, and tsan can handle a maximum of 8192 concurrent threads at one time. Limit the number of concurrent threads. It is difficult to do this in a way that does not involve a child being blocked on a parent completing to spin up goroutines for itself to complete. Solve this by completing work on the main thread if there are no additional workers available to help complete work. I was expecting limiting the concurrency to hurt performance, but it actually significantly improves it. Benchmarks were performed using CL 94904 at tip, and with goroutines at 2, 4, and 8 times the number of CPU's. $ benchstat tip.benchmark gated-2.benchmark gated-4.benchmark gated-8.benchmark name \ time/op tip.benchmark gated-2.benchmark gated-4.benchmark gated-8.benchmark NewDirectory-4 293ms ± 2% 262ms ± 4% 252ms ± 4% 253ms ± 2% name \ alloc/op tip.benchmark gated-2.benchmark gated-4.benchmark gated-8.benchmark NewDirectory-4 218MB ± 0% 218MB ± 0% 218MB ± 0% 218MB ± 0% name \ allocs/op tip.benchmark gated-2.benchmark gated-4.benchmark gated-8.benchmark NewDirectory-4 513k ± 0% 508k ± 0% 509k ± 0% 510k ± 0% Fixes golang/go#22110. Change-Id: If01f78f1fc53cd195e4f8f6988c3c39b3c275992 Reviewed-on: https://go-review.googlesource.com/94955 Reviewed-by: Yury Smolsky <yury@smolsky.by> Reviewed-by: Kevin Burke <kev@inburke.com> |
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README.md
Go Tools
This subrepository holds the source for various packages and tools that support the Go programming language.
Some of the tools, godoc and vet for example, are included in binary Go
distributions.
Others, including the Go guru and the test coverage tool, can be fetched with
go get.
Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.
Download/Install
The easiest way to install is to run go get -u golang.org/x/tools/.... You can
also manually git clone the repository to $GOPATH/src/golang.org/x/tools.
Report Issues / Send Patches
This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.
The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with "x/tools/(your subdir):" in the subject line, so it is easy to find.