runtime: impose thread count limit
Actually working to stay within the limit could cause subtle deadlocks.
Crashing avoids the subtlety.
Fixes #4056.
R=golang-dev, r, dvyukov
CC=golang-dev
https://golang.org/cl/13037043
diff --git a/src/pkg/runtime/crash_test.go b/src/pkg/runtime/crash_test.go
index 7ea1b6b..e07810b 100644
--- a/src/pkg/runtime/crash_test.go
+++ b/src/pkg/runtime/crash_test.go
@@ -125,6 +125,14 @@
}
}
+func TestThreadExhaustion(t *testing.T) {
+ output := executeTest(t, threadExhaustionSource, nil)
+ want := "runtime: program exceeds 10-thread limit\nfatal error: thread exhaustion"
+ if !strings.HasPrefix(output, want) {
+ t.Fatalf("output does not start with %q:\n%s", want, output)
+ }
+}
+
const crashSource = `
package main
@@ -243,3 +251,25 @@
return x[0] + f(buf[:])
}
`
+
+const threadExhaustionSource = `
+package main
+
+import (
+ "runtime"
+ "runtime/debug"
+)
+
+func main() {
+ debug.SetMaxThreads(10)
+ c := make(chan int)
+ for i := 0; i < 100; i++ {
+ go func() {
+ runtime.LockOSThread()
+ c <- 0
+ select{}
+ }()
+ <-c
+ }
+}
+`
