tree 2f70978d0a710c7c2a01603538bab7756bff367c
parent 1e1ec013b916a41f3dffeb3699ee9dfc44bc5470
author Josh Bleecher Snyder <josharian@gmail.com> 1524509620 -0700
committer Josh Bleecher Snyder <josharian@gmail.com> 1525199235 +0000

cmd/guru: parallelize loop in globalReferrersPkgLevel

This change parallelizes the outer loop in globalReferrersPkgLevel,
which loops over packages to inspect.

There is also an easily parallelizable inner loop.
However, parallelizing it adds complication
(deffiles needs a mutex, inQueryPackage requires a wait group)
and offers only a 2% speed-up.

Benchmarks for this change, looking for encoding/json.MarshalIndent:

name       old time/op       new time/op       delta
Referrers        5.31s ± 2%        4.67s ± 3%  -11.95%  (p=0.000 n=10+10)

name       old user-time/op  new user-time/op  delta
Referrers        15.9s ± 2%        16.5s ± 3%   +3.71%  (p=0.000 n=10+10)

name       old sys-time/op   new sys-time/op   delta
Referrers        15.7s ± 3%        16.1s ± 3%   +2.73%  (p=0.011 n=10+10)


Fixes golang/go#24272
Updates golang/go#25017


This work supported by Sourcegraph.

Change-Id: I5dcda9017103cdff59d0ffdf5e87d2c2c955a33a
Reviewed-on: https://go-review.googlesource.com/108878
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>