src: call uv_library_shutdown before DisposePlatform

When the process exits, there may be tasks in the thread pool
that need to access data in the platform, such as trace agent.
So make sure the thread pool exits first.
see #44458

PR-URL: #45226
Refs: #44458
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>

Author: theanarkh

src/api/environment.cc

@@ -779,8 +779,13 @@ void DefaultProcessExitHandler(Environment* env, int exit_code) {
   env->set_can_call_into_js(false);
   env->stop_sub_worker_contexts();
   env->isolate()->DumpAndResetStats();
-  DisposePlatform();
+  // When the process exits, the tasks in the thread pool may also need to
+  // access the data of V8Platform, such as trace agent, or a field
+  // added in the future. So make sure the thread pool exits first.
+  // And make sure V8Platform don not call into Libuv threadpool, see Dispose
+  // in node_v8_platform-inl.h
   uv_library_shutdown();
+  DisposePlatform();
   exit(exit_code);
 }
 

src/node_v8_platform-inl.h

@@ -103,7 +103,8 @@ struct V8Platform {
     platform_ = new NodePlatform(thread_pool_size, controller);
     v8::V8::InitializePlatform(platform_);
   }
-
+  // Make sure V8Platform don not call into Libuv threadpool,
+  // see DefaultProcessExitHandlerInternal in environment.cc
   inline void Dispose() {
     if (!initialized_)
       return;