unlock worker thread

use postMessage from the main thread instead of atomics to signal the worker

lib/internal/modules/esm/hooks.js

@@ -453,12 +453,15 @@ class HooksProxy {
   #data;
   /**
    * The lock/unlock segment of the shared memory. Atomics require this to be a Int32Array. This
-   * segment is used to tell the main to sleep when the worker is processing, and vice versa
-   * (for the worker to sleep whilst the main thread is processing).
+   * segment is used to tell the main to sleep when the worker is processing.
    * 0 -> main sleeps
-   * 1 -> worker sleeps
+   * 1 -> main wakes up
    */
   #lock;
+  /**
+   * A MessagePort used to synchronously communicate with the worker.
+   */
+  #syncCommPort;
 
   #isReady = false;
 
@@ -468,11 +471,14 @@ class HooksProxy {
    */
   constructor() {
     const { InternalWorker } = require('internal/worker');
+    const { MessageChannel } = require('internal/worker/io');
 
     const data = new SharedArrayBuffer(204_800);
     const lock = new SharedArrayBuffer(4);
     this.#data = new Uint8Array(data);
     this.#lock = new Int32Array(lock);
+    const syncCommChannel = new MessageChannel();
+    this.#syncCommPort = syncCommChannel.port1;
 
     const worker = this.worker = new InternalWorker('internal/modules/esm/worker', {
       stderr: false,
@@ -482,9 +488,11 @@ class HooksProxy {
       workerData: {
         data,
         lock,
+        syncCommPort: syncCommChannel.port2,
       },
+      transferList: [syncCommChannel.port2],
     });
-    worker.unref(); // ! Allows the process to eventually exit when worker is in its final sleep.
+    worker.unref(); // ! Allows the process to eventually exit.
   }
 
   makeRequest(method, ...args) {
@@ -501,6 +509,9 @@ class HooksProxy {
     const request = serialize({ method, args });
     TypedArrayPrototypeSet(this.#data, request);
 
+    // Signal the worker that there is work to do.
+    this.#syncCommPort.postMessage(true);
+
     const chunks = [];
     let done = false;
     try {

lib/internal/modules/esm/worker.js

@@ -23,6 +23,7 @@ const { workerData } = require('worker_threads');
 // lock = 1 -> worker sleeps
 const lock = new Int32Array(workerData.lock); // Required by Atomics
 const data = new Uint8Array(workerData.data); // For v8.deserialize/serialize
+const { syncCommPort } = workerData; // To receive work signals.
 const CHUNK_THRESHOLD = data.length - 26; // `{ done: true/false, value: … }` adds 26 bytes
 
 function releaseLock() {
@@ -46,14 +47,14 @@ function releaseLock() {
     initializationError = exception;
   }
 
+  syncCommPort.on('message', handleSyncMessage);
+
   // ! Put as little above this line as possible
   releaseLock(); // Send 'ready' signal to main
 
   const { deserialize, serialize } = require('v8');
 
-  while (true) { // The loop is needed in order to cycle through requests
-    Atomics.wait(lock, 0, 1); // This pauses the while loop
-
+  async function handleSyncMessage() {
     const { method, args } = deserialize(data);
     TypedArrayPrototypeFill(data, undefined);