async_wrap: schedule destroy hook as unref

Since the `DestroyAsyncIdsCallback` in Node.js can be scheduled as
a result of GC, that means that it can accidentally keep the event
loop open when it shouldn't.

Replace `SetImmediate` with the newly introduced `SetUnrefImmediate`
and in addition introduce RunBeforeExit callbacks, of which
`DestroyAsyncIdsCallback` is now the first. These callbacks will run
before the `beforeExit` event is emitted (which will now only be
emitted if the event loop is still not active).

PR-URL: https://github.com/nodejs/node/pull/18241
Fixes: https://github.com/nodejs/node/issues/18190
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Andreas Madsen <amwebdk@gmail.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/async_wrap.cc b/src/async_wrap.cc
index f770348b9c9..5258674ff33 100644
--- a/src/async_wrap.cc
+++ b/src/async_wrap.cc
@@ -159,6 +159,12 @@ static void DestroyAsyncIdsCallback(Environment* env, void* data) {
   } while (!env->destroy_async_id_list()->empty());
 }
 
+static void DestroyAsyncIdsCallback(void* arg) {
+  Environment* env = static_cast<Environment*>(arg);
+  if (!env->destroy_async_id_list()->empty())
+    DestroyAsyncIdsCallback(env, nullptr);
+}
+
 
 void AsyncWrap::EmitPromiseResolve(Environment* env, double async_id) {
   AsyncHooks* async_hooks = env->async_hooks();
@@ -502,6 +508,8 @@ void AsyncWrap::Initialize(Local<Object> target,
   Isolate* isolate = env->isolate();
   HandleScope scope(isolate);
 
+  env->BeforeExit(DestroyAsyncIdsCallback, env);
+
   env->SetMethod(target, "setupHooks", SetupHooks);
   env->SetMethod(target, "pushAsyncIds", PushAsyncIds);
   env->SetMethod(target, "popAsyncIds", PopAsyncIds);
@@ -663,7 +671,7 @@ void AsyncWrap::EmitDestroy(Environment* env, double async_id) {
     return;
 
   if (env->destroy_async_id_list()->empty()) {
-    env->SetImmediate(DestroyAsyncIdsCallback, nullptr);
+    env->SetUnrefImmediate(DestroyAsyncIdsCallback, nullptr);
   }
 
   env->destroy_async_id_list()->push_back(async_id);