2 files changed, 43 insertions, 19 deletions
diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go
index eb7231aec2..e45bc7a770 100644
--- a/src/runtime/mprof.go
+++ b/src/runtime/mprof.go
@@ -522,34 +522,46 @@ func ThreadCreateProfile(p []StackRecord) (n int, ok bool) {
 // Most clients should use the runtime/pprof package instead
 // of calling GoroutineProfile directly.
 func GoroutineProfile(p []StackRecord) (n int, ok bool) {
+	gp := getg()
+
+	isOK := func(gp1 *g) bool {
+		// Checking isSystemGoroutine here makes GoroutineProfile
+		// consistent with both NumGoroutine and Stack.
+		return gp1 != gp && readgstatus(gp1) != _Gdead && !isSystemGoroutine(gp1)
+	}
+
+	stopTheWorld("profile")
+
+	n = 1
+	for _, gp1 := range allgs {
+		if isOK(gp1) {
+			n++
+		}
+	}
 
-	n = NumGoroutine()
 	if n <= len(p) {
-		gp := getg()
-		stopTheWorld("profile")
+		ok = true
+		r := p
 
-		n = NumGoroutine()
-		if n <= len(p) {
-			ok = true
-			r := p
-			sp := getcallersp(unsafe.Pointer(&p))
-			pc := getcallerpc(unsafe.Pointer(&p))
-			systemstack(func() {
-				saveg(pc, sp, gp, &r[0])
-			})
-			r = r[1:]
-			for _, gp1 := range allgs {
-				if gp1 == gp || readgstatus(gp1) == _Gdead {
-					continue
-				}
+		// Save current goroutine.
+		sp := getcallersp(unsafe.Pointer(&p))
+		pc := getcallerpc(unsafe.Pointer(&p))
+		systemstack(func() {
+			saveg(pc, sp, gp, &r[0])
+		})
+		r = r[1:]
+
+		// Save other goroutines.
+		for _, gp1 := range allgs {
+			if isOK(gp1) {
 				saveg(^uintptr(0), ^uintptr(0), gp1, &r[0])
 				r = r[1:]
 			}
 		}
-
-		startTheWorld()
 	}
 
+	startTheWorld()
+
 	return n, ok
 }
 
diff --git a/src/runtime/runtime_test.go b/src/runtime/runtime_test.go
index 664c1180c4..581f52bcb0 100644
--- a/src/runtime/runtime_test.go
+++ b/src/runtime/runtime_test.go
@@ -308,3 +308,15 @@ func TestAppendSliceGrowth(t *testing.T) {
 		}
 	}
 }
+
+func TestGoroutineProfileTrivial(t *testing.T) {
+	n1, ok := GoroutineProfile(nil) // should fail, there's at least 1 goroutine
+	if n1 < 1 || ok {
+		t.Fatalf("GoroutineProfile(nil) = %d, %v, want >0, false", n1, ok)
+	}
+
+	n2, ok := GoroutineProfile(make([]StackRecord, n1))
+	if n2 != n1 || !ok {
+		t.Fatalf("GoroutineProfile(%d) = %d, %v, want %d, true", n1, n2, ok, n1)
+	}
+}