src: fix node watchdog race condition

PR-URL: #43780
Fixes: #43699
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

src/node_watchdog.cc

@@ -102,6 +102,7 @@ void Watchdog::Timer(uv_timer_t* timer) {
 SigintWatchdog::SigintWatchdog(
   v8::Isolate* isolate, bool* received_signal)
     : isolate_(isolate), received_signal_(received_signal) {
+  Mutex::ScopedLock lock(SigintWatchdogHelper::GetInstanceActionMutex());
   // Register this watchdog with the global SIGINT/Ctrl+C listener.
   SigintWatchdogHelper::GetInstance()->Register(this);
   // Start the helper thread, if that has not already happened.
@@ -110,6 +111,7 @@ SigintWatchdog::SigintWatchdog(
 
 
 SigintWatchdog::~SigintWatchdog() {
+  Mutex::ScopedLock lock(SigintWatchdogHelper::GetInstanceActionMutex());
   SigintWatchdogHelper::GetInstance()->Unregister(this);
   SigintWatchdogHelper::GetInstance()->Stop();
 }
@@ -144,6 +146,7 @@ void TraceSigintWatchdog::New(const FunctionCallbackInfo<Value>& args) {
 void TraceSigintWatchdog::Start(const FunctionCallbackInfo<Value>& args) {
   TraceSigintWatchdog* watchdog;
   ASSIGN_OR_RETURN_UNWRAP(&watchdog, args.Holder());
+  Mutex::ScopedLock lock(SigintWatchdogHelper::GetInstanceActionMutex());
   // Register this watchdog with the global SIGINT/Ctrl+C listener.
   SigintWatchdogHelper::GetInstance()->Register(watchdog);
   // Start the helper thread, if that has not already happened.
@@ -154,6 +157,7 @@ void TraceSigintWatchdog::Start(const FunctionCallbackInfo<Value>& args) {
 void TraceSigintWatchdog::Stop(const FunctionCallbackInfo<Value>& args) {
   TraceSigintWatchdog* watchdog;
   ASSIGN_OR_RETURN_UNWRAP(&watchdog, args.Holder());
+  Mutex::ScopedLock lock(SigintWatchdogHelper::GetInstanceActionMutex());
   SigintWatchdogHelper::GetInstance()->Unregister(watchdog);
   SigintWatchdogHelper::GetInstance()->Stop();
 }
@@ -215,6 +219,7 @@ void TraceSigintWatchdog::HandleInterrupt() {
   signal_flag_ = SignalFlags::None;
   interrupting = false;
 
+  Mutex::ScopedLock lock(SigintWatchdogHelper::GetInstanceActionMutex());
   SigintWatchdogHelper::GetInstance()->Unregister(this);
   SigintWatchdogHelper::GetInstance()->Stop();
   raise(SIGINT);
@@ -413,6 +418,7 @@ SigintWatchdogHelper::~SigintWatchdogHelper() {
 }
 
 SigintWatchdogHelper SigintWatchdogHelper::instance;
+Mutex SigintWatchdogHelper::instance_action_mutex_;
 
 namespace watchdog {
 static void Initialize(Local<Object> target,

src/node_watchdog.h

@@ -110,6 +110,7 @@ class TraceSigintWatchdog : public HandleWrap, public SigintWatchdogBase {
 class SigintWatchdogHelper {
  public:
   static SigintWatchdogHelper* GetInstance() { return &instance; }
+  static Mutex& GetInstanceActionMutex() { return instance_action_mutex_; }
   void Register(SigintWatchdogBase* watchdog);
   void Unregister(SigintWatchdogBase* watchdog);
   bool HasPendingSignal();
@@ -123,6 +124,7 @@ class SigintWatchdogHelper {
 
   static bool InformWatchdogsAboutSignal();
   static SigintWatchdogHelper instance;
+  static Mutex instance_action_mutex_;
 
   int start_stop_count_;
 

test/parallel/test-vm-break-on-sigint.js

@@ -0,0 +1,22 @@
+'use strict';
+const common = require('../common');
+
+// This test ensures that running vm with breakOnSignt option in multiple
+// worker_threads does not crash.
+// Issue: https://github.com/nodejs/node/issues/43699
+const { Worker } = require('worker_threads');
+const vm = require('vm');
+
+// Don't use isMainThread to allow running this test inside a worker.
+if (!process.env.HAS_STARTED_WORKER) {
+  process.env.HAS_STARTED_WORKER = 1;
+  for (let i = 0; i < 10; i++) {
+    const worker = new Worker(__filename);
+    worker.on('exit', common.mustCall());
+  }
+} else {
+  const ctx = vm.createContext({});
+  for (let i = 0; i < 10000; i++) {
+    vm.runInContext('console.log(1)', ctx, { breakOnSigint: true });
+  }
+}