1 files changed, 125 insertions, 0 deletions
diff --git a/src/pkg/runtime/proc_test.go b/src/pkg/runtime/proc_test.go
new file mode 100644
index 000000000..32111080a
--- /dev/null
+++ b/src/pkg/runtime/proc_test.go
@@ -0,0 +1,125 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"runtime"
+	"sync/atomic"
+	"testing"
+)
+
+var stop = make(chan bool, 1)
+
+func perpetuumMobile() {
+	select {
+	case <-stop:
+	default:
+		go perpetuumMobile()
+	}
+}
+
+func TestStopTheWorldDeadlock(t *testing.T) {
+	if testing.Short() {
+		t.Logf("skipping during short test")
+		return
+	}
+	maxprocs := runtime.GOMAXPROCS(3)
+	compl := make(chan bool, 2)
+	go func() {
+		for i := 0; i != 1000; i += 1 {
+			runtime.GC()
+		}
+		compl <- true
+	}()
+	go func() {
+		for i := 0; i != 1000; i += 1 {
+			runtime.GOMAXPROCS(3)
+		}
+		compl <- true
+	}()
+	go perpetuumMobile()
+	<-compl
+	<-compl
+	stop <- true
+	runtime.GOMAXPROCS(maxprocs)
+}
+
+func stackGrowthRecursive(i int) {
+	var pad [128]uint64
+	if i != 0 && pad[0] == 0 {
+		stackGrowthRecursive(i - 1)
+	}
+}
+
+func BenchmarkStackGrowth(b *testing.B) {
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	c := make(chan bool, procs)
+	for p := 0; p < procs; p++ {
+		go func() {
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for g := 0; g < CallsPerSched; g++ {
+					stackGrowthRecursive(10)
+				}
+			}
+			c <- true
+		}()
+	}
+	for p := 0; p < procs; p++ {
+		<-c
+	}
+}
+
+func BenchmarkSyscall(b *testing.B) {
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	c := make(chan bool, procs)
+	for p := 0; p < procs; p++ {
+		go func() {
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for g := 0; g < CallsPerSched; g++ {
+					runtime.Entersyscall()
+					runtime.Exitsyscall()
+				}
+			}
+			c <- true
+		}()
+	}
+	for p := 0; p < procs; p++ {
+		<-c
+	}
+}
+
+func BenchmarkSyscallWork(b *testing.B) {
+	const CallsPerSched = 1000
+	const LocalWork = 100
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	c := make(chan bool, procs)
+	for p := 0; p < procs; p++ {
+		go func() {
+			foo := 42
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for g := 0; g < CallsPerSched; g++ {
+					runtime.Entersyscall()
+					for i := 0; i < LocalWork; i++ {
+						foo *= 2
+						foo /= 2
+					}
+					runtime.Exitsyscall()
+				}
+			}
+			c <- foo == 42
+		}()
+	}
+	for p := 0; p < procs; p++ {
+		<-c
+	}
+}