worker: use _writev in internal communication

PR-URL: #33454
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: addaleax

lib/internal/main/worker_thread.js

@@ -167,8 +167,9 @@ port.on('message', (message) => {
       CJSLoader.Module.runMain(filename);
     }
   } else if (message.type === STDIO_PAYLOAD) {
-    const { stream, chunk, encoding } = message;
-    process[stream].push(chunk, encoding);
+    const { stream, chunks } = message;
+    for (const { chunk, encoding } of chunks)
+      process[stream].push(chunk, encoding);
   } else {
     assert(
       message.type === STDIO_WANTS_MORE_DATA,

lib/internal/worker.js

@@ -243,8 +243,11 @@ class Worker extends EventEmitter {
         return this[kOnErrorMessage](message.error);
       case messageTypes.STDIO_PAYLOAD:
       {
-        const { stream, chunk, encoding } = message;
-        return this[kParentSideStdio][stream].push(chunk, encoding);
+        const { stream, chunks } = message;
+        const readable = this[kParentSideStdio][stream];
+        for (const { chunk, encoding } of chunks)
+          readable.push(chunk, encoding);
+        return;
       }
       case messageTypes.STDIO_WANTS_MORE_DATA:
       {

lib/internal/worker/io.js

@@ -206,12 +206,11 @@ class WritableWorkerStdio extends Writable {
     this[kWritableCallbacks] = [];
   }
 
-  _write(chunk, encoding, cb) {
+  _writev(chunks, cb) {
     this[kPort].postMessage({
       type: messageTypes.STDIO_PAYLOAD,
       stream: this[kName],
-      chunk,
-      encoding
+      chunks: chunks.map(({ chunk, encoding }) => ({ chunk, encoding }))
     });
     this[kWritableCallbacks].push(cb);
     if (this[kPort][kWaitingStreams]++ === 0)
@@ -222,7 +221,7 @@ class WritableWorkerStdio extends Writable {
     this[kPort].postMessage({
       type: messageTypes.STDIO_PAYLOAD,
       stream: this[kName],
-      chunk: null
+      chunks: [ { chunk: null, encoding: '' } ]
     });
     cb();
   }