runtime: ensure forward progress of runtime.Gosched() for locked goroutines
The removed code leads to the situation when M executes the same locked G again
and again.
This is https://golang.org/cl/7310096 but with return instead of break
in the nested switch.
Fixes #4820.
R=golang-dev, alex.brainman, rsc
CC=golang-dev
https://golang.org/cl/7304102
diff --git a/src/pkg/runtime/proc_test.go b/src/pkg/runtime/proc_test.go
index 927bd7b..1f727da 100644
--- a/src/pkg/runtime/proc_test.go
+++ b/src/pkg/runtime/proc_test.go
@@ -46,6 +46,36 @@
runtime.GOMAXPROCS(maxprocs)
}
+func TestYieldProgress(t *testing.T) {
+ testYieldProgress(t, false)
+}
+
+func TestYieldLockedProgress(t *testing.T) {
+ testYieldProgress(t, true)
+}
+
+func testYieldProgress(t *testing.T, locked bool) {
+ c := make(chan bool)
+ cack := make(chan bool)
+ go func() {
+ if locked {
+ runtime.LockOSThread()
+ }
+ for {
+ select {
+ case <-c:
+ cack <- true
+ return
+ default:
+ runtime.Gosched()
+ }
+ }
+ }()
+ time.Sleep(10 * time.Millisecond)
+ c <- true
+ <-cack
+}
+
func TestYieldLocked(t *testing.T) {
const N = 10
c := make(chan bool)
