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Katharine Berry 7defa796fe cover: significantly improve the speed of cover.ParseProfiles
ParseProfiles currently uses a regex to parse each line. This is not
very fast, and can lead to ParseProfiles being excessively slow on
certain pathological inputs.

This change substantially improves the performance by parsing manually
instead. On an input of about 3 GB of data containing about 36 million
lines, the time spent in ParseProfiles drops from 72 seconds to 11
seconds, with actual string parsing time dropping from 61 seconds to 2
seconds.

Since this change completely changes the parsing, it also adds some
tests for ParseProfiles to help ensure the new parsing is correct.

A benchmark for parseLine is also included. Here is a comparison of the old
regex implementation versus the new manual one:

name          old time/op    new time/op      delta
ParseLine-12    2.43µs ± 2%      0.05µs ± 8%    -97.98%  (p=0.000 n=10+9)

name          old speed      new speed        delta
ParseLine-12  42.5MB/s ± 2%  2103.2MB/s ± 7%  +4853.14%  (p=0.000 n=10+9)

Fixes golang/go#32211

Change-Id: If8f91ecbda776c08243de4e423de4eea55f0082b
Reviewed-on: https://go-review.googlesource.com/c/tools/+/179377
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-24 07:44:52 +00:00
benchmark/parse benchmark/parse: fix cosmetic defect in error str. 2015-02-02 17:07:43 +00:00
blog blog: add support for optional analytics HTML 2019-10-02 16:18:51 +00:00
cmd cmd/present: fix origin mismatch for websocket when using HTTPS 2019-10-14 20:52:21 +00:00
container/intsets x/tools/container/intsets: add LowerBound 2017-08-21 16:11:21 +00:00
cover cover: significantly improve the speed of cover.ParseProfiles 2019-10-24 07:44:52 +00:00
go go/analysis/passes/inspect: fix incorrect example 2019-10-23 14:34:23 +00:00
godoc godoc/vfs/zipfs: fix godoc formatting 2019-10-07 15:17:16 +00:00
gopls gopls: update go.mod file 2019-10-21 18:45:54 +00:00
imports imports: allow nil Options in Process 2019-05-20 22:08:59 +00:00
internal internal/telemetry/export/ocagent: attach timestamps to metrics 2019-10-24 07:31:07 +00:00
playground playground: use stdlib instead of appengine packages 2019-03-07 16:39:23 +00:00
present all: replace reference to plan9.bell-labs.com with 9p.io 2019-08-26 06:06:29 +00:00
refactor all: fix more typos 2019-09-11 15:13:14 +00:00
.gitattributes tools: copying .gitattributes to all subrepositories (fixes windows build) 2014-12-23 06:32:51 +00:00
.gitignore .gitignore: roll back ".gitignore: ignore emacs backup files" 2018-02-13 00:43:28 +00:00
AUTHORS go.empty: prototype for new subrepository 2012-01-25 14:45:13 -05:00
codereview.cfg tools: add codereview.cfg 2015-03-18 17:04:00 +00:00
CONTRIBUTING.md CONTRIBUTING.md: remove note about not accepting Pull Requests 2018-03-14 18:02:17 +00:00
CONTRIBUTORS go.empty: prototype for new subrepository 2012-01-25 14:45:13 -05:00
go.mod internal/lsp: use x/xerrors to create new errors 2019-08-06 19:46:56 +00:00
go.sum internal/lsp: use protocol.Ranges for source.Identifier 2019-08-29 05:14:58 +00:00
LICENSE LICENSE: add 2012-03-17 15:20:58 +11:00
PATENTS go.empty: add PATENTS file to the subrepo. 2012-04-16 11:24:04 +10:00
README.md README: switch to Markdown and add links 2017-09-27 05:40:07 +00:00

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.