async_hooks: avoid GC tracking of AsyncResource in ALS

Flarna · addaleax · commit 148383fdc3cc · 2020-09-22T23:48:04.000+02:00
Manually destroy the AsyncResource created by AsyncLocalStore.run() to avoid unneeded GC tracking in case a destroy hooks is present. PR-URL: #34653 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: James M Snell <jasnell@gmail.com>
diff --git a/lib/async_hooks.js b/lib/async_hooks.js
@@ -250,6 +250,7 @@ const storageHook = createHook({
   }
 });
 
+const defaultAlsResourceOpts = { requireManualDestroy: true };
 class AsyncLocalStorage {
   constructor() {
     this.kResourceStore = Symbol('kResourceStore');
@@ -290,8 +291,11 @@ class AsyncLocalStorage {
     if (ObjectIs(store, this.getStore())) {
       return callback(...args);
     }
-    const resource = new AsyncResource('AsyncLocalStorage');
-    return resource.runInAsyncScope(() => {
+    const resource = new AsyncResource('AsyncLocalStorage',
+                                       defaultAlsResourceOpts);
+    // Calling emitDestroy before runInAsyncScope avoids a try/finally
+    // It is ok because emitDestroy only schedules calling the hook
+    return resource.emitDestroy().runInAsyncScope(() => {
       this.enterWith(store);
       return callback(...args);
     });
