separate worker data & lock buffers

Author: JakobJingleheimer

lib/internal/modules/esm/hooks.js

@@ -446,23 +446,19 @@ ObjectSetPrototypeOf(Hooks.prototype, null);
 
 class HooksProxy {
   /**
-   * The communication vehicle constituting all memory shared between the main and the worker.
+   * The request & response segment of the shared memory. TextEncoder/Decoder (needed to convert
+   * requests & responses into a format supported by the comms channel) reads and writes with
+   * Uint8Array.
    */
-  #commsChannel = new SharedArrayBuffer(2048); // maybe use buffer.constants.MAX_LENGTH ?
+  #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).
    * 0 -> main sleeps
    * 1 -> worker sleeps
    */
-  #lock = new Int32Array(this.#commsChannel, 0, 4);
-  /**
-   * The request & response segment of the shared memory. TextEncoder/Decoder (needed to convert
-   * requests & responses into a format supported by the comms channel) reads and writes with
-   * Uint8Array.
-   */
-  #requestResponseData = new Uint8Array(this.#commsChannel, 4, 2044);
+  #lock;
 
   #isReady = false;
 
@@ -472,12 +468,21 @@ class HooksProxy {
    */
   constructor() {
     const { InternalWorker } = require('internal/worker');
+
+    const data = new SharedArrayBuffer(2048);
+    const lock = new SharedArrayBuffer(4);
+    this.#data = new Uint8Array(data);
+    this.#lock = new Int32Array(lock);
+
     const worker = this.worker = new InternalWorker('internal/modules/esm/worker', {
       stderr: false,
       stdin: false,
       stdout: false,
       trackUnmanagedFds: false,
-      workerData: { commsChannel: this.#commsChannel },
+      workerData: {
+        data,
+        lock,
+      },
     });
     worker.unref(); // ! Allows the process to eventually exit when worker is in its final sleep.
   }
@@ -492,20 +497,20 @@ class HooksProxy {
       this.#isReady = true;
     }
 
-    TypedArrayPrototypeFill(this.#requestResponseData, 0); // Erase handled request/response data
+    TypedArrayPrototypeFill(this.#data, 0); // Erase handled request/response data
 
     const request = serialize({ method, args });
-    TypedArrayPrototypeSet(this.#requestResponseData, request);
+    TypedArrayPrototypeSet(this.#data, request);
 
     Atomics.store(this.#lock, 0, 0); // Send request to worker
     Atomics.notify(this.#lock, 0); // Notify worker of new request
     Atomics.wait(this.#lock, 0, 0); // Sleep until worker responds
 
     let response;
     try {
-      response = deserialize(this.#requestResponseData);
+      response = deserialize(this.#data);
     } catch (exception) {
-      if (this.#requestResponseData.every((byte) => byte === 0)) {
+      if (this.#data.every((byte) => byte === 0)) {
         throw new ERR_INVALID_RETURN_VALUE('an object', method, undefined);
       } else {
         throw exception;

lib/internal/modules/esm/worker.js

@@ -21,13 +21,11 @@ internalBinding('module_wrap').callbackMap = new SafeWeakMap();
 
 const { isMainThread, workerData } = require('worker_threads');
 if (isMainThread) { return; } // Needed to pass some tests that happen to load this file on the main thread
-const { commsChannel } = workerData;
 
 // lock = 0 -> main sleeps
 // lock = 1 -> worker sleeps
-const lock = new Int32Array(commsChannel, 0, 4); // Required by Atomics
-const requestResponseDataSize = 2044;
-const requestResponseData = new Uint8Array(commsChannel, 4, requestResponseDataSize); // For v8.deserialize/serialize
+const lock = new Int32Array(workerData.lock); // Required by Atomics
+const data = new Uint8Array(workerData.data); // For v8.deserialize/serialize
 
 function releaseLock() {
   Atomics.store(lock, 0, 1); // Send response to main
@@ -58,8 +56,8 @@ function releaseLock() {
   while (true) {
     Atomics.wait(lock, 0, 1); // This pauses the while loop
 
-    const { method, args } = deserialize(requestResponseData);
-    TypedArrayPrototypeFill(requestResponseData, 0);
+    const { method, args } = deserialize(data);
+    TypedArrayPrototypeFill(data, 0);
 
     // Each potential exception needs to be caught individually so that the correct error is sent to the main thread
     let response, serializedResponse;
@@ -78,19 +76,19 @@ function releaseLock() {
 
     try {
       serializedResponse = serialize(response);
-      if (serializedResponse.byteLength > requestResponseDataSize) {
-        throw new ERR_OUT_OF_RANGE('serializedResponse.byteLength', `<= ${requestResponseDataSize}`, serializedResponse.byteLength);
+      if (serializedResponse.byteLength > data.length) {
+        throw new ERR_OUT_OF_RANGE('serializedResponse.byteLength', `<= ${data.length}`, serializedResponse.byteLength);
       }
     } catch (exception) {
       serializedResponse = serialize(exception);
     }
 
     // Send the method response (or exception) to the main thread
     try {
-      TypedArrayPrototypeSet(requestResponseData, serializedResponse);
+      TypedArrayPrototypeSet(data, serializedResponse);
     } catch (exception) {
       // Or send the exception thrown when trying to send the response
-      TypedArrayPrototypeSet(requestResponseData, serialize(exception));
+      TypedArrayPrototypeSet(data, serialize(exception));
     }
     releaseLock();
   }