From: Carl Shapiro <cshapiro@google.com>
Date: Sat, 21 Sep 2013 00:27:56 +0000 (-0700)
Subject: test/chan: avoid wrap-around in memstats comparison
X-Git-Tag: go1.2rc2~153
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=1c45f98fa38d9600ee1c60c2bfba3c0dced86087;p=gostls13.git

test/chan: avoid wrap-around in memstats comparison

The select2.go test assumed that the memory allocated between
its two samplings of runtime.ReadMemStats is strictly
increasing.  To avoid failing the tests when this is not true,
a greater-than check is introduced before computing the
difference in allocated memory.

R=golang-dev, r, cshapiro
CC=golang-dev
https://golang.org/cl/13701046
---

diff --git a/test/chan/select2.go b/test/chan/select2.go
index 4a08139126..ccf9dab81b 100644
--- a/test/chan/select2.go
+++ b/test/chan/select2.go
@@ -47,7 +47,8 @@ func main() {
 	runtime.GC()
 	runtime.ReadMemStats(memstats)
 
-	if memstats.Alloc-alloc > 1.1e5 {
+	// Be careful to avoid wraparound.
+	if memstats.Alloc > alloc && memstats.Alloc-alloc > 1.1e5 {
 		println("BUG: too much memory for 100,000 selects:", memstats.Alloc-alloc)
 	}
 }