fix Atomics locks

lib/internal/modules/esm/public_loader_proxy.js

@@ -10,6 +10,8 @@ const commsChannel = new SharedArrayBuffer(2048);
  * 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 worker, and vice verse (for the
  * worker to sleep whilst the main is working).
+ * 0 → main sleeps
+ * 1 → worker sleeps
  */
 const lock = new Int32Array(commsChannel, 0, 4);
 /**
@@ -24,15 +26,15 @@ const worker = new Worker('./worker.js', {
 });
 worker.unref(); // ! Allows the process to eventually exit when worker is in its final sleep.
 
-Atomics.wait(lock, 0, 1); // ! Block this module until the worker is ready.
+Atomics.wait(lock, 0, 0); // ! Block this module until the worker is ready.
 
 function makeRequest(type, data) {
   requestResponseData.fill(0); // Erase any previous request/response (it's already been handled)
-  Atomics.store(lock, 0, 1); // Send request to worker
   const request = serialize({ data, type });
   requestResponseData.set(request);
+  Atomics.store(lock, 0, 0); // Send request to worker
   Atomics.notify(lock, 0); // Notify worker of new request
-  Atomics.wait(lock, 0, 1); // Sleep until worker responds
+  Atomics.wait(lock, 0, 0); // Sleep until worker responds
   return deserialize(requestResponseData);
 }
 

lib/internal/modules/esm/worker.js

@@ -3,14 +3,13 @@ const { workerData } = require('internal/worker_threads');
 const { deserialize, serialize } = require('v8');
 
 const { commsChannel } = workerData;
+// lock = 0 → main sleeps
+// lock = 1 → worker sleeps
 const lock = new Int32Array(commsChannel, 0, 4); // Required by Atomics
 const requestResponseData = new Uint8Array(commsChannel, 4, 2044); // for TextEncoder/Decoder
 
 const publicESMLoader = new ESMLoader();
 
-Atomics.store(lock, 0, 0); // Send 'ready' signal to main
-Atomics.notify(lock, 0); // Notify main of signal
-
 const types = {
   'addCustomLoaders': publicESMLoader.addCustomLoaders,
   'cjsCache.delete': publicESMLoader.cjsCache.delete,
@@ -21,13 +20,16 @@ const types = {
   'resolve': publicESMLoader.resolve,
 };
 
+Atomics.store(lock, 0, 1); // Send 'ready' signal to main
+Atomics.notify(lock, 0); // Notify main of signal
+
 while (true) { // event loop
-  Atomics.wait(lock, 0, 0); // This pauses the while loop
+  Atomics.wait(lock, 0, 1); // This pauses the while loop
   // Worker is now active and main is sleeping
   const { data, type } = deserialize(requestResponseData);
   const response = await types[type](data);
   requestResponseData.fill(0);
-  Atomics.store(lock, 0, 0); // Send response to main
   requestResponseData.set(serialize(response));
+  Atomics.store(lock, 0, 1); // Send response to main
   Atomics.notify(lock, 0); // Notify main of new response
 };