code review 141800043: testing: read coverage counters atomically

testing: read coverage counters atomically
For -mode=atomic, we need to read the counters
using an atomic load to avoid a race. Not worth worrying
about when -mode=atomic is set during generation
of the profile, so we use atomic loads always.

Fixes issue 8630.

[r, 2014-09-08 21:39:38]

Hello dvyukov (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go

[rsc, 2014-09-09 18:50:40]

LGTM

[r, 2014-09-09 19:31:10]

*** Submitted as https://code.google.com/p/go/source/detail?r=605db9b526f4 ***

testing: read coverage counters atomically
For -mode=atomic, we need to read the counters
using an atomic load to avoid a race. Not worth worrying
about when -mode=atomic is set during generation
of the profile, so we use atomic loads always.

Fixes issue 8630.

LGTM=rsc
R=dvyukov, rsc
CC=golang-codereviews
https://codereview.appspot.com/141800043

[gobot, 2014-09-09 22:05:49]

This CL appears to have broken the windows-amd64-perf builder.
See http://build.golang.org/log/27649e84a89c7feba439522e1db6e27a98b9289e