time: fix deadlock in Sleep(0)
See time/sleep_test.go for repro.
R=golang-dev, r, rsc
CC=golang-dev, patrick.allen.higgins
https://golang.org/cl/6250072
diff --git a/src/pkg/time/sleep_test.go b/src/pkg/time/sleep_test.go
index 526d58d..e05773d 100644
--- a/src/pkg/time/sleep_test.go
+++ b/src/pkg/time/sleep_test.go
@@ -223,3 +223,25 @@
}
Sleep(3 * Second)
}
+
+func TestSleepZeroDeadlock(t *testing.T) {
+ // Sleep(0) used to hang, the sequence of events was as follows.
+ // Sleep(0) sets G's status to Gwaiting, but then immediately returns leaving the status.
+ // Then the goroutine calls e.g. new and falls down into the scheduler due to pending GC.
+ // After the GC nobody wakes up the goroutine from Gwaiting status.
+ defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
+ c := make(chan bool)
+ go func() {
+ for i := 0; i < 100; i++ {
+ runtime.GC()
+ }
+ c <- true
+ }()
+ for i := 0; i < 100; i++ {
+ Sleep(0)
+ tmp := make(chan bool, 1)
+ tmp <- true
+ <-tmp
+ }
+ <-c
+}
