From a899a467f2e8ef7af2153cb91063f2da2bc2f36f Mon Sep 17 00:00:00 2001
From: Dmitriy Vyukov <dvyukov@google.com>
Date: Fri, 25 Nov 2011 14:13:10 +0300
Subject: [PATCH] time: fix timer stop Due to data structure corruption, some
 timers could not be removed. Fixes #2495.

R=golang-dev, adg
CC=golang-dev, mdbrown
https://golang.org/cl/5437060
---
 src/pkg/runtime/time.goc   | 13 ++++++++++---
 src/pkg/time/sleep_test.go | 16 ++++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/pkg/runtime/time.goc b/src/pkg/runtime/time.goc
index 23ad1aaef7e..ad9f3aac564 100644
--- a/src/pkg/runtime/time.goc
+++ b/src/pkg/runtime/time.goc
@@ -133,9 +133,16 @@ deltimer(Timer *t)
 		return false;
 	}
 
-	timers.t[i] = timers.t[--timers.len];
-	siftup(i);
-	siftdown(i);
+	timers.len--;
+	if(i == timers.len) {
+		timers.t[i] = nil;
+	} else {
+		timers.t[i] = timers.t[timers.len];
+		timers.t[timers.len] = nil;
+		timers.t[i]->i = i;
+		siftup(i);
+		siftdown(i);
+	}
 	runtime·unlock(&timers);
 	return true;
 }
diff --git a/src/pkg/time/sleep_test.go b/src/pkg/time/sleep_test.go
index 4c4a079880a..6fa2b69c509 100644
--- a/src/pkg/time/sleep_test.go
+++ b/src/pkg/time/sleep_test.go
@@ -205,3 +205,19 @@ func testAfterQueuing(t *testing.T) error {
 	}
 	return nil
 }
+
+func TestTimerStopStress(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+	for i := 0; i < 100; i++ {
+		go func(i int) {
+			timer := AfterFunc(2e9, func() {
+				t.Fatalf("timer %d was not stopped", i)
+			})
+			Sleep(1e9)
+			timer.Stop()
+		}(i)
+	}
+	Sleep(3e9)
+}