From 6fedd50b8e4e9874128879a6f8d828667c3ecac1 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Sat, 23 Dec 2023 10:58:53 +0100
Subject: [PATCH] lib: run microtasks before ticks

This resolve multiple timing issues related to promises
and nextTick. As well as resolving zaldo in promise only
code, i.e. our current best practice of using process.nextTick
will always apply and work.

Refs: https://github.com/nodejs/node/issues/51156
Refs: https://github.com/nodejs/node/issues/51156#issuecomment-1864656761
Refs: https://github.com/nodejs/node/pull/51114
Refs: https://github.com/nodejs/node/pull/51070
Refs: https://github.com/nodejs/node/issues/51156

PR-URL: https://github.com/nodejs/node/pull/51267
---
 doc/api/cli.md                      | 15 +++++++++++++++
 lib/internal/process/task_queues.js | 13 ++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/doc/api/cli.md b/doc/api/cli.md
index c17af97f38b3fd..da3e9691eba6c1 100644
--- a/doc/api/cli.md
+++ b/doc/api/cli.md
@@ -789,6 +789,21 @@ about [this configuration][`--experimental-sea-config`] for details.
 
 ### `--experimental-shadow-realm`
 
+### `--experimental-task-ordering`
+
+Enable experimental task ordering. Always drain micro task queue
+before running `process.nextTick` to avoid unintuitive behavior
+and unexpected logical deadlocks when mixing async callback and
+event API's with `Promise`, `async`/`await`` and `queueMicroTask`.
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+
+
 <!-- YAML
 added:
   - v19.0.0
diff --git a/lib/internal/process/task_queues.js b/lib/internal/process/task_queues.js
index bcb5eef841dd00..82768885b5b6ff 100644
--- a/lib/internal/process/task_queues.js
+++ b/lib/internal/process/task_queues.js
@@ -41,6 +41,7 @@ const {
 
 const { AsyncResource } = require('async_hooks');
 
+let experimentalTaskOrdering;
 // *Must* match Environment::TickInfo::Fields in src/env.h.
 const kHasTickScheduled = 0;
 
@@ -65,8 +66,16 @@ function runNextTicks() {
 }
 
 function processTicksAndRejections() {
+  if (experimentalTaskOrdering === undeifned) {
+    const { getOptionValue } = require('internal/options');
+    experimentalTaskOrdering = getOptionValue('--experimental-task-ordering');
+  }
+
   let tock;
   do {
+    if (experimentalTaskOrdering) {
+      runMicrotasks();
+    }
     while ((tock = queue.shift()) !== null) {
       const asyncId = tock[async_id_symbol];
       emitBefore(asyncId, tock[trigger_async_id_symbol], tock);
@@ -92,7 +101,9 @@ function processTicksAndRejections() {
 
       emitAfter(asyncId);
     }
-    runMicrotasks();
+    if (!experimentalTaskOrdering) {
+      runMicrotasks();
+    }
   } while (!queue.isEmpty() || processPromiseRejections());
   setHasTickScheduled(false);
   setHasRejectionToWarn(false);