From: Michael Pratt <mpratt@google.com>
Date: Fri, 9 Feb 2024 19:16:11 +0000 (-0500)
Subject: internal/trace: fix race condition in gc-stress
X-Git-Tag: go1.23rc1~1257
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=09c62a86a96e51d535336de1c7b7e10cd3acd849;p=gostls13.git

internal/trace: fix race condition in gc-stress

Multiple goroutines all writing to the same sink triggers the race detector,
rightfully so.

Change-Id: Ia64836d0d88c0f587a6cb96ed747f656a3c1804a
Reviewed-on: https://go-review.googlesource.com/c/go/+/562997
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
---

diff --git a/src/internal/trace/v2/testdata/testprog/gc-stress.go b/src/internal/trace/v2/testdata/testprog/gc-stress.go
index 70d3a246c3..017f7f07bf 100644
--- a/src/internal/trace/v2/testdata/testprog/gc-stress.go
+++ b/src/internal/trace/v2/testdata/testprog/gc-stress.go
@@ -39,7 +39,7 @@ func makeTree(depth int) *node {
 
 var trees [16]*node
 var ballast *[16]*[8192]*node
-var sink []byte
+var sink [][]byte
 
 func main() {
 	for i := range trees {
@@ -54,10 +54,15 @@ func main() {
 			}
 		}
 	}
-	for i := 0; i < runtime.GOMAXPROCS(-1); i++ {
+
+	procs := runtime.GOMAXPROCS(-1)
+	sink = make([][]byte, procs)
+
+	for i := 0; i < procs; i++ {
+		i := i
 		go func() {
 			for {
-				sink = make([]byte, rand.Intn(32<<10))
+				sink[i] = make([]byte, rand.Intn(32<<10))
 			}
 		}()
 	}