runtime: fix finalizer iterator

It could only handle one finalizer before it raised an out-of-bounds error.

Fixes issue #9172

Change-Id: Ibb4d0c8aff2d78a1396e248c7129a631176ab427
Reviewed-on: https://go-review.googlesource.com/1201
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/src/runtime/debug/heapdump_test.go b/src/runtime/debug/heapdump_test.go
index 9201901151..cf01f52015 100644
--- a/src/runtime/debug/heapdump_test.go
+++ b/src/runtime/debug/heapdump_test.go
@@ -31,3 +31,40 @@ func TestWriteHeapDumpNonempty(t *testing.T) {
 		t.Fatalf("Heap dump size %d bytes, expected at least %d bytes", size, minSize)
 	}
 }
+
+
+type Obj struct {
+       x, y int
+}
+
+func objfin(x *Obj) {
+       println("finalized", x)
+}
+
+func TestWriteHeapDumpFinalizers(t *testing.T) {
+	if runtime.GOOS == "nacl" {
+		t.Skip("WriteHeapDump is not available on NaCl.")
+	}
+	f, err := ioutil.TempFile("", "heapdumptest")
+	if err != nil {
+		t.Fatalf("TempFile failed: %v", err)
+	}
+	defer os.Remove(f.Name())
+	defer f.Close()
+
+	// bug 9172: WriteHeapDump couldn't handle more than one finalizer
+	println("allocating objects")
+	x := &Obj{}
+	runtime.SetFinalizer(x, objfin)
+	y := &Obj{}
+	runtime.SetFinalizer(y, objfin)
+
+	// Trigger collection of x and y, queueing of their finalizers.
+	println("starting gc")
+	runtime.GC()
+
+	// Make sure WriteHeapDump doesn't fail with multiple queued finalizers.
+	println("starting dump")
+	WriteHeapDump(f.Fd())
+	println("done dump")
+}