1 files changed, 108 insertions, 0 deletions
diff --git a/src/runtime/testdata/testprogcgo/notingo.go b/src/runtime/testdata/testprogcgo/notingo.go
new file mode 100644
index 0000000000..e5b1062e9e
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/notingo.go
@@ -0,0 +1,108 @@
+// Copyright 2025 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.
+
+//go:build !plan9 && !windows
+// +build !plan9,!windows
+
+package main
+
+/*
+#include <stdatomic.h>
+#include <stddef.h>
+#include <pthread.h>
+
+extern void Ready();
+
+static int spinning;
+static int released;
+
+static void* enterGoThenSpinTwice(void* arg __attribute__ ((unused))) {
+	Ready();
+	atomic_fetch_add(&spinning, 1);
+	while(atomic_load(&released) == 0) {};
+
+	Ready();
+	atomic_fetch_add(&spinning, 1);
+	while(1) {};
+	return NULL;
+}
+
+static void SpinTwiceInNewCThread() {
+	pthread_t tid;
+	pthread_create(&tid, NULL, enterGoThenSpinTwice, NULL);
+}
+
+static int Spinning() {
+	return atomic_load(&spinning);
+}
+
+static void Release() {
+	atomic_store(&spinning, 0);
+	atomic_store(&released, 1);
+}
+*/
+import "C"
+
+import (
+	"os"
+	"runtime"
+	"runtime/metrics"
+)
+
+func init() {
+	register("NotInGoMetricCallback", NotInGoMetricCallback)
+}
+
+func NotInGoMetricCallback() {
+	const N = 10
+	s := []metrics.Sample{{Name: "/sched/goroutines/not-in-go:goroutines"}}
+
+	// Create N new C threads that have called into Go at least once.
+	for range N {
+		C.SpinTwiceInNewCThread()
+	}
+
+	// Synchronize with spinning threads twice.
+	//
+	// This helps catch bad accounting by taking at least a couple other
+	// codepaths which would cause the accounting to change.
+	for i := range 2 {
+		// Make sure they pass through Go.
+		// N.B. Ready is called twice by the new threads.
+		for j := range N {
+			<-readyCh
+			if j == 2 {
+				// Try to trigger an update in the immediate STW handoff case.
+				runtime.ReadMemStats(&m)
+			}
+		}
+
+		// Make sure they're back in C.
+		for C.Spinning() < N {
+		}
+
+		// Do something that stops the world to take all the Ps back.
+		runtime.ReadMemStats(&m)
+
+		if i == 0 {
+			C.Release()
+		}
+	}
+
+	// Read not-in-go.
+	metrics.Read(s)
+	if n := s[0].Value.Uint64(); n != 0 {
+		println("expected 0 not-in-go goroutines, found", n)
+		os.Exit(2)
+	}
+	println("OK")
+}
+
+var m runtime.MemStats
+var readyCh = make(chan bool)
+
+//export Ready
+func Ready() {
+	readyCh <- true
+}