async_hooks: move to lazy destroy hook registration in AsyncResource

puzpuzpuz · targos · commit b63223114bd3 · 2020-04-11T10:12:56.000+02:00
PR-URL: #32429 Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de> Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
diff --git a/benchmark/async_hooks/gc-tracking.js b/benchmark/async_hooks/gc-tracking.js
@@ -1,11 +1,12 @@
 'use strict';
 const common = require('../common.js');
-const { AsyncResource } = require('async_hooks');
+const { createHook, AsyncResource } = require('async_hooks');
 
 const bench = common.createBenchmark(main, {
   n: [1e6],
   method: [
     'trackingEnabled',
+    'trackingEnabledWithDestroyHook',
     'trackingDisabled',
   ]
 }, {
@@ -30,6 +31,14 @@ function main({ n, method }) {
       }
       endAfterGC(n);
       break;
+    case 'trackingEnabledWithDestroyHook':
+      createHook({ destroy: () => {} }).enable();
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        new AsyncResource('foobar');
+      }
+      endAfterGC(n);
+      break;
     case 'trackingDisabled':
       bench.start();
       for (let i = 0; i < n; i++) {
diff --git a/doc/api/async_hooks.md b/doc/api/async_hooks.md
@@ -685,6 +685,8 @@ asyncResource.triggerAsyncId();
   when the object is garbage collected. This usually does not need to be set
   (even if `emitDestroy` is called manually), unless the resource's `asyncId`
   is retrieved and the sensitive API's `emitDestroy` is called with it.
+  When set to `false`, the `emitDestroy` call on garbage collection
+  will only take place if there is at least one active `destroy` hook.
   **Default:** `false`.
 
 Example usage:
diff --git a/lib/async_hooks.js b/lib/async_hooks.js
@@ -36,6 +36,7 @@ const {
   emitDestroy,
   enabledHooksExist,
   initHooksExist,
+  destroyHooksExist,
 } = internal_async_hooks;
 
 // Get symbols
@@ -168,7 +169,7 @@ class AsyncResource {
       emitInit(asyncId, type, triggerAsyncId, this);
     }
 
-    if (!requireManualDestroy) {
+    if (!requireManualDestroy && destroyHooksExist()) {
       // This prop name (destroyed) has to be synchronized with C++
       const destroyed = { destroyed: false };
       this[destroyedSymbol] = destroyed;
