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: nodejs#51156
Refs: nodejs#51156 (comment)
Refs: nodejs#51114
Refs: nodejs#51070
Refs: nodejs#51156

PR-URL: nodejs#51267

Author: ronag

doc/api/cli.md

@@ -863,6 +863,20 @@ Use this flag to generate a blob that can be injected into the Node.js
 binary to produce a [single executable application][]. See the documentation
 about [this configuration][`--experimental-sea-config`] for details.
 
+
+### `--experimental-task-ordering`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+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`.
+
 ### `--experimental-shadow-realm`
 
 <!-- YAML

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 === undefined) {
+    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);
@@ -163,10 +174,11 @@ module.exports = {
     // Sets the per-isolate promise rejection callback
     listenForRejections();
     // Sets the callback to be run in every tick.
-    setTickCallback(processTicksAndRejections);
+    setTickCallback(processTicksAndRejections
+    );
     return {
       nextTick,
-      runNextTicks,
+      runNextTicks
     };
   },
   queueMicrotask,