From a3c1a3f40120b4cf6a5e24025a0279a8c48ea22f Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Wed, 27 Jan 2016 16:21:33 -0500 Subject: [PATCH] runtime: deflake TestNumGoroutine Fixes #14107. Change-Id: Icd9463b1a77b139c7ebc2d8732482d704ea332d0 Reviewed-on: https://go-review.googlesource.com/19002 Reviewed-by: Brad Fitzpatrick --- src/runtime/proc_test.go | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/src/runtime/proc_test.go b/src/runtime/proc_test.go index 34d90a1c9b..9e5960bd2a 100644 --- a/src/runtime/proc_test.go +++ b/src/runtime/proc_test.go @@ -345,12 +345,27 @@ func TestNumGoroutine(t *testing.T) { } buf := make([]byte, 1<<20) - buf = buf[:runtime.Stack(buf, true)] - n := runtime.NumGoroutine() + // Try up to 10 times for a match before giving up. + // This is a fundamentally racy check but it's important + // to notice if NumGoroutine and Stack are _always_ out of sync. + for i := 0; ; i++ { + // Give goroutines about to exit a chance to exit. + // The NumGoroutine and Stack below need to see + // the same state of the world, so anything we can do + // to keep it quiet is good. + runtime.Gosched() + + n := runtime.NumGoroutine() + buf = buf[:runtime.Stack(buf, true)] - if nstk := strings.Count(string(buf), "goroutine "); n != nstk { - t.Fatalf("NumGoroutine=%d, but found %d goroutines in stack dump: %s", n, nstk, buf) + nstk := strings.Count(string(buf), "goroutine ") + if n == nstk { + break + } + if i >= 10 { + t.Fatalf("NumGoroutine=%d, but found %d goroutines in stack dump: %s", n, nstk, buf) + } } } -- 2.48.1