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author | Josh Bleecher Snyder <josharian@gmail.com> | 2017-07-07 13:09:20 -1000 |
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committer | Josh Bleecher Snyder <josharian@gmail.com> | 2017-07-08 02:10:12 +0000 |
commit | a1e7fb4eed7fbb002d2fabbd6a809a1a49dca711 (patch) | |
tree | 2d9099210b76b4081f9b0942c6b7f07f29950413 | |
parent | 093adeef4004fd029de1a8fd138802607265dc73 (diff) | |
download | go-a1e7fb4eed7fbb002d2fabbd6a809a1a49dca711.tar.gz go-a1e7fb4eed7fbb002d2fabbd6a809a1a49dca711.zip |
test: deflake chan/select3.go
On a slow or distracted machine, 0.1s is sometimes
not long enough for a non-blocking function call to complete.
This causes rare test flakes.
They can be easily reproduced by reducing the wait time to (say) 100ns.
For non-blocking functions, increase the window from 100ms to 10s.
Using different windows for block and non-blocking functions,
allows us to reduce the time for blocking functions.
The risk here is false negatives, but that risk is low;
this test is run repeatedly on many fast machines,
for which 10ms is ample time.
This reduces the time required to run the test by a factor of 10,
from ~1s to ~100ms.
Fixes #20299
Change-Id: Ice9a641a66c6c101d738a2ebe1bcb144ae3c9916
Reviewed-on: https://go-review.googlesource.com/47812
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
-rw-r--r-- | test/chan/select3.go | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/test/chan/select3.go b/test/chan/select3.go index e9391f55c7..dd14c7381e 100644 --- a/test/chan/select3.go +++ b/test/chan/select3.go @@ -40,8 +40,15 @@ func testBlock(signal string, f func()) { c <- never // f didn't block }() go func() { - time.Sleep(1e8) // 0.1s seems plenty long - c <- always // f blocked always + if signal == never { + // Wait a long time to make sure that we don't miss our window by accident on a slow machine. + time.Sleep(10 * time.Second) + } else { + // Wait as short a time as we can without false negatives. + // 10ms should be long enough to catch most failures. + time.Sleep(10 * time.Millisecond) + } + c <- always // f blocked always }() if <-c != signal { panic(signal + " block") |