[Core] Show_webui segfault fix. (#8323)

src/ray/core_worker/core_worker.cc

@@ -590,6 +590,13 @@ void CoreWorker::WaitForShutdown() {
   }
   if (options_.worker_type == WorkerType::WORKER) {
     RAY_CHECK(task_execution_service_.stopped());
+    // Asyncio coroutines could still run after CoreWorker is removed because it is
+    // running in a different thread. This can cause segfault because coroutines try to
+    // access CoreWorker methods that are already garbage collected. We should complete
+    // all coroutines before shutting down in order to prevent this.
+    if (worker_context_.CurrentActorIsAsync()) {
+      options_.terminate_asyncio_thread();
+    }
   }
 }
 

src/ray/core_worker/core_worker.h

@@ -114,6 +114,8 @@ struct CoreWorkerOptions {
   bool is_local_mode;
   /// The number of workers to be started in the current process.
   int num_workers;
+  /// The function to destroy asyncio event and loops.
+  std::function<void()> terminate_asyncio_thread;
 };
 
 /// Lifecycle management of one or more `CoreWorker` instances in a process.