MessageChannel

Learn inter-worker channels with MessageChannel.

MessageChannel

MessageChannel creates two connected ports: port1 and port2. A message written to one port appears as a "message" event on the other. This lets you set up a direct communication channel between workers.

A typical use: the main thread creates a MessageChannel, transfers port2 to a worker with worker.postMessage(msg, [port2]). Now two workers can talk to each other without going through the parent. This reduces the parent bottleneck when you have many workers.

port1 and port2

When you create a MessageChannel you get port1 and port2. Calling port1.postMessage(data) fires port2.on("message", handler), and vice versa.

Ports are EventEmitters; you listen for on("message"), on("close") and similar events. You may need to call port.start() to activate a port; otherwise messages queue up. When done, close the port with port.close().

Exercise Log the type of port1.postMessage

Import the MessageChannel class. Create a new channel. Log typeof port1.postMessage.

Show example solution

const { MessageChannel } = require("worker_threads");
const { port1, port2 } = new MessageChannel();
console.log(typeof port1.postMessage);

Test yourself

What does MessageChannel create?
- Tek bir port
- Two connected ports
- Three separate channels
- A thread
Show answer

Two connected ports — MessageChannel creates two connected ports.
Match each piece to its role

MessageChannel

Creates two ports
port1

One side
port2

Other side
port.postMessage

Sends message

Complete the class name

const { port1, port2 } = new ____()

Show answer

const { port1, port2 } = new MessageChannel()

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