misc/cgo/test: flaky test: TestParallelSleep

[bradfitz]

We need to fix this flaky test:

http://build.golang.org/log/4fb532043c73801a467007afc6a8d27b3b7018ad

# ..\misc\cgo\test
--- FAIL: TestParallelSleep (1.81 seconds)
        basic.go:598: sleep(1) slept for 1.805s
        basic.go:603: parallel 1-second sleeps slept for 1.805000 seconds
FAIL
scatter = 00498FDB


This happens a lot.

[minux]

Comment 1:

we've wasted too much effort on this particular flakiness:
revision f6668796d52c, revision 18a0bd67b4b4, revision 16fcd7235fad;

[bradfitz]

Comment 2:

But we need to fix it.  Failure noise isn't acceptable.  We need to either delete it or
fix it.  But ignoring flaky tests isn't an option.

[minux]

Comment 3:

i agree. let's try once more, if it's still flaky, let's skip the test in -short mode
and use -short
mode for run.bash. ok?
could we record and compare the start time of the sleep rather than the end time of the
sleep?
because we ultimately concerns about starting the two sleeps concurrently rather than
serially
so comparing start time might be more reliable than end time.

[alexbrainman]

Comment 4:

#3 minux.ma has a good plan :-). Skip it! I have wasted enough time there.
Alex

[minux]

Comment 5:

https://golang.org/cl/9475043

Owner changed to @minux.

Status changed to Started.

[minux]

Comment 6:

This issue was closed by revision af1dd56.

Status changed to Fixed.

[gopherbot]

Comment 7 by tegoor:

# ..\misc\cgo\test
--- FAIL: TestParallelSleep (1.03 seconds)
        basic.go:563: difference in start time for two sleep(1) is 36757h25m57.1
58s
        basic.go:568: parallel 1-second sleeps slept for 132326757.158000 second
s
FAIL
scatter = 0049863F
hello from C
FAIL    _/D_/golang/misc/cgo/test       1.844s

[minux]

Comment 8:

how could two GetTickCount() returns vastly different values?

[minux]

Comment 9:

just for the record, failure in #7 is actually another real bug, see issue #5603.

[davecheney]

Comment 10:

@9, wow, i'm amazed that this test actually caught a real bug for once.

[minux]

Comment 11:

yeah, and i'm glad we don't skip the test when #7 is reported.