Explicit shutdown of TimerManager to ensure this is done on the main thread

packages/react-native/ReactCommon/react/runtime/PlatformTimerRegistry.h

@@ -25,6 +25,8 @@ class PlatformTimerRegistry {
   virtual void createRecurringTimer(uint32_t timerID, double delayMS) = 0;
 
   virtual ~PlatformTimerRegistry() noexcept = default;
+
+  virtual void quit() {}
 };
 
 using TimerManagerDelegate = PlatformTimerRegistry;

packages/react-native/ReactCommon/react/runtime/ReactInstance.cpp

@@ -162,6 +162,11 @@ ReactInstance::ReactInstance(
         runtimeScheduler->scheduleWork(std::move(callback));
       });
 }
+ReactInstance::~ReactInstance() noexcept {
+  if (timerManager_ != nullptr) {
+    timerManager_->quit();
+  }
+}
 
 void ReactInstance::unregisterFromInspector() {
   if (inspectorTarget_ != nullptr) {
@@ -184,8 +189,8 @@ RuntimeExecutor ReactInstance::getUnbufferedRuntimeExecutor() noexcept {
 
 // This BufferedRuntimeExecutor ensures that the main JS bundle finished
 // execution before any JS queued into it from C++ are executed. Use
-// getUnbufferedRuntimeExecutor() instead if you do not need the main JS bundle
-// to have finished. e.g. setting global variables into JS runtime.
+// getUnbufferedRuntimeExecutor() instead if you do not need the main JS
+// bundle to have finished. e.g. setting global variables into JS runtime.
 RuntimeExecutor ReactInstance::getBufferedRuntimeExecutor() noexcept {
   return [weakBufferedRuntimeExecutor_ =
               std::weak_ptr<BufferedRuntimeExecutor>(bufferedRuntimeExecutor_)](
@@ -219,8 +224,8 @@ std::string simpleBasename(const std::string& path) {
  * Load the JS bundle and flush buffered JS calls, future JS calls won't be
  * buffered after calling this.
  * Note that this method is asynchronous. However, a completion callback
- * isn't needed because all calls into JS should be dispatched to the JSThread,
- * preferably via the runtimeExecutor_.
+ * isn't needed because all calls into JS should be dispatched to the
+ * JSThread, preferably via the runtimeExecutor_.
  */
 void ReactInstance::loadScript(
     std::unique_ptr<const JSBigString> script,

packages/react-native/ReactCommon/react/runtime/ReactInstance.h

@@ -31,6 +31,8 @@ class ReactInstance final : private jsinspector_modern::InstanceTargetDelegate {
       JsErrorHandler::OnJsError onJsError,
       jsinspector_modern::HostTarget *parentInspectorTarget = nullptr);
 
+  ~ReactInstance() noexcept;
+
   RuntimeExecutor getUnbufferedRuntimeExecutor() noexcept;
 
   RuntimeExecutor getBufferedRuntimeExecutor() noexcept;

packages/react-native/ReactCommon/react/runtime/TimerManager.cpp

@@ -56,6 +56,18 @@ TimerManager::TimerManager(
     std::unique_ptr<PlatformTimerRegistry> platformTimerRegistry) noexcept
     : platformTimerRegistry_(std::move(platformTimerRegistry)) {}
 
+TimerManager::~TimerManager() noexcept {
+  quit();
+}
+
+void TimerManager::quit() {
+  if (platformTimerRegistry_ == nullptr) {
+    return;
+  }
+  platformTimerRegistry_->quit();
+  platformTimerRegistry_ = nullptr;
+}
+
 void TimerManager::setRuntimeExecutor(
     RuntimeExecutor runtimeExecutor) noexcept {
   runtimeExecutor_ = std::move(runtimeExecutor);

packages/react-native/ReactCommon/react/runtime/TimerManager.h

@@ -46,13 +46,16 @@ struct TimerCallback {
 class TimerManager {
  public:
   explicit TimerManager(std::unique_ptr<PlatformTimerRegistry> platformTimerRegistry) noexcept;
+  ~TimerManager() noexcept;
 
   void setRuntimeExecutor(RuntimeExecutor runtimeExecutor) noexcept;
 
   void callTimer(TimerHandle handle);
 
   void attachGlobals(jsi::Runtime &runtime);
 
+  void quit();
+
  private:
   TimerHandle createTimer(
       jsi::Function &&callback,

packages/react-native/ReactCxxPlatform/react/runtime/platform/cxx/react/runtime/PlatformTimerRegistryImpl.cpp

@@ -12,10 +12,8 @@
 
 namespace facebook::react {
 
-PlatformTimerRegistryImpl::~PlatformTimerRegistryImpl() noexcept {
-  LOG(INFO)
-      << "PlatformTimerRegistryImpl::~PlatformTimerRegistryImpl() was called (address: "
-      << this << ").";
+void PlatformTimerRegistryImpl::quit() {
+  LOG(INFO) << "Shutting down PlatformTimerRegistryImpl...";
   taskDispatchThread_.quit();
   std::lock_guard<std::mutex> guard(timersMutex_);
   timers_.clear();

packages/react-native/ReactCxxPlatform/react/runtime/platform/cxx/react/runtime/PlatformTimerRegistryImpl.h

@@ -23,7 +23,7 @@ class PlatformTimerRegistryImpl : public PlatformTimerRegistry {
   PlatformTimerRegistryImpl &operator=(const PlatformTimerRegistryImpl &) = delete;
   PlatformTimerRegistryImpl(PlatformTimerRegistryImpl &&) noexcept = delete;
   PlatformTimerRegistryImpl &operator=(PlatformTimerRegistryImpl &&) noexcept = delete;
-  ~PlatformTimerRegistryImpl() noexcept override;
+  ~PlatformTimerRegistryImpl() noexcept = default;
 
   void createTimer(uint32_t timerId, double delayMs) override;
 
@@ -33,6 +33,8 @@ class PlatformTimerRegistryImpl : public PlatformTimerRegistry {
 
   void setTimerManager(std::weak_ptr<TimerManager> timerManager);
 
+  void quit() override;
+
  private:
   struct Timer {
     uint32_t timerId{0};