process: add deferTick

Adds a new scheduling primitive to resolve zaldo when mixing
traditional Node async programming with async/await and Promises.

We cannot "fix" nextTick without breaking the whole ecosystem.
nextTick usage should be discouraged and we should try to
incrementally move to this new primitive.

TODO:
- [] Fill in concrete examples
- [] Add tests
- [] Add benchmarks
- [] Do we need async hook logic or not?
- [] process._exiting?
- [] Anything else we are unhappy with in regard to nextTick which
     we want to fix?

doc/api/process.md

@@ -1219,6 +1219,25 @@ const process = require('node:process');
 process.debugPort = 5858;
 ```
 
+## `process.deferTick(callback[, ...args])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `callback` {Function}
+* `...args` {any} Additional arguments to pass when invoking the `callback`
+
+`process.deferTick()` adds `callback` to the "defer tick queue". This queue is
+fully drained after the current operation on the JavaScript stack runs to
+completion and before the event loop is allowed to continue. It's possible to
+create an infinite loop if one were to recursively call `process.deferTick()`.
+See the [Event Loop][] guide for more background.
+
+Unlike `process.nextTick`, `process.deferTick()` will run after the "next tick
+queue" and the microtask queue has been fully drained as to avoid zaldo when
+combinding traditional node asynchronous code with Promises.
+
 ## `process.disconnect()`
 
 <!-- YAML

lib/internal/bootstrap/node.js

@@ -303,8 +303,9 @@ process.emitWarning = emitWarning;
 // bootstrap to make sure that any operation done before this are synchronous.
 // If any ticks or timers are scheduled before this they are unlikely to work.
 {
-  const { nextTick, runNextTicks } = setupTaskQueue();
+  const { nextTick, runNextTicks, deferTick } = setupTaskQueue();
   process.nextTick = nextTick;
+  process.deferTick = deferTick;
   // Used to emulate a tick manually in the JS land.
   // A better name for this function would be `runNextTicks` but
   // it has been exposed to the process object so we keep this legacy name

lib/internal/process/task_queues.js

@@ -53,6 +53,7 @@ function setHasTickScheduled(value) {
 }
 
 const queue = new FixedQueue();
+const deferQueue = new FixedQueue();
 
 // Should be in sync with RunNextTicksNative in node_task_queue.cc
 function runNextTicks() {
@@ -93,6 +94,10 @@ function processTicksAndRejections() {
       emitAfter(asyncId);
     }
     runMicrotasks();
+
+    let tmp = queue;
+    queue = deferQueue;
+    deferQueue = tmp;
   } while (!queue.isEmpty() || processPromiseRejections());
   setHasTickScheduled(false);
   setHasRejectionToWarn(false);
@@ -133,6 +138,31 @@ function nextTick(callback) {
   queue.push(tickObject);
 }
 
+function deferTick(callback, ...args) {
+  validateFunction(callback, 'callback');
+
+  if (process._exiting)
+    return;
+
+  if (tickInfo[kHasTickScheduled] === 0) {
+    tickInfo[kHasTickScheduled] = 1;
+  }
+
+  const asyncId = newAsyncId();
+  const triggerAsyncId = getDefaultTriggerAsyncId();
+  const tickObject = {
+    [async_id_symbol]: asyncId,
+    [trigger_async_id_symbol]: triggerAsyncId,
+    callback,
+    args,
+  };
+
+  if (initHooksExist())
+    emitInit(asyncId, 'TickObject', triggerAsyncId, tickObject);
+
+  deferQueue.push(tickObject);
+}
+
 function runMicrotask() {
   this.runInAsyncScope(() => {
     const callback = this.callback;
@@ -166,6 +196,7 @@ module.exports = {
     setTickCallback(processTicksAndRejections);
     return {
       nextTick,
+      deferTick,
       runNextTicks,
     };
   },

test/async-hooks/test-defertick.js

@@ -0,0 +1,15 @@
+'use strict';
+
+const common = require('../common');
+const { EventEmitter } = require('events');
+
+setImmediate(async () => {
+  const e = await new Promise((resolve) => {
+    const e = new EventEmitter();
+    resolve(e);
+    process.deferTick(common.mustCall(() => {
+      e.emit('error', new Error('kaboom'));
+    }));
+  });
+  e.on('error', common.mustCall(() => {}));
+});