fix: prevent hang when process is overwritten (#83)

src/entry/process.ts

@@ -23,6 +23,9 @@ process.__tinypool_state__ = {
   workerId: Number(process.env.TINYPOOL_WORKER_ID),
 }
 
+const memoryUsage = process.memoryUsage.bind(process)
+const send = process.send!.bind(process)
+
 process.on('message', (message: IncomingMessage) => {
   // Message was not for port or pool
   // It's likely end-users own communication between main and worker
@@ -36,7 +39,7 @@ process.on('message', (message: IncomingMessage) => {
         await getHandler(filename, name)
       }
 
-      process.send!(<OutgoingMessage>{
+      send!(<OutgoingMessage>{
         ready: true,
         source: 'pool',
         __tinypool_worker_message__: true,
@@ -69,7 +72,7 @@ async function onMessage(message: IncomingMessage & { source: 'port' }) {
       taskId,
       result,
       error: null,
-      usedMemory: process.memoryUsage().heapUsed,
+      usedMemory: memoryUsage().heapUsed,
     }
 
     // If the task used e.g. console.log(), wait for the stream to drain
@@ -89,11 +92,11 @@ async function onMessage(message: IncomingMessage & { source: 'port' }) {
       taskId,
       result: null,
       error: serializeError(error),
-      usedMemory: process.memoryUsage().heapUsed,
+      usedMemory: memoryUsage().heapUsed,
     }
   }
 
-  process.send!(response)
+  send!(response)
 }
 
 function serializeError(error: unknown) {

src/entry/worker.ts

@@ -28,6 +28,7 @@ process.__tinypool_state__ = {
   workerId: tinypoolPrivateData.workerId,
 }
 
+const memoryUsage = process.memoryUsage.bind(process)
 let useAtomics: boolean = process.env.PISCINA_DISABLE_ATOMICS !== '1'
 
 // We should only receive this message once, when the Worker starts. It gives
@@ -110,7 +111,7 @@ function onMessage(
         taskId,
         result: result,
         error: null,
-        usedMemory: process.memoryUsage().heapUsed,
+        usedMemory: memoryUsage().heapUsed,
       }
 
       // If the task used e.g. console.log(), wait for the stream to drain
@@ -130,7 +131,7 @@ function onMessage(
         // It may be worth taking a look at the error cloning algorithm we
         // use in Node.js core here, it's quite a bit more flexible
         error,
-        usedMemory: process.memoryUsage().heapUsed,
+        usedMemory: memoryUsage().heapUsed,
       }
     }
     currentTasks--

test/globals.test.ts

@@ -0,0 +1,32 @@
+import * as path from 'path'
+import { fileURLToPath } from 'url'
+import { Tinypool } from 'tinypool'
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+
+describe.each(['worker_threads', 'child_process'] as const)('%s', (runtime) => {
+  test("doesn't hang when process is overwritten", async () => {
+    const pool = createPool({ runtime })
+
+    const result = await pool.run(`
+    (async () => {
+      return new Promise(resolve => {
+        globalThis.process = { exit: resolve };
+        process.exit("exit() from overwritten process");
+      });
+    })();
+    `)
+    expect(result).toBe('exit() from overwritten process')
+  })
+})
+
+function createPool(options: Partial<Tinypool['options']>) {
+  const pool = new Tinypool({
+    filename: path.resolve(__dirname, 'fixtures/eval.js'),
+    minThreads: 1,
+    maxThreads: 1,
+    ...options,
+  })
+
+  return pool
+}