jarle/Bun Spawn a child process and communicate using IPC

Spawn a child process and communicate using IPC

Use Bun.spawn() to spawn a child process. When spawning a second bun process, you can open a direct inter-process communication (IPC) channel between the two processes.

<Note> This API is only compatible with other `bun` processes. Use `process.execPath` to get a path to the currently running `bun` executable. </Note>

const child = Bun.spawn(["bun", "child.ts"], {
  ipc(message) {
    /**
     * The message received from the sub process
     **/
  },
});

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The parent process can send messages to the subprocess using the .send() method on the returned Subprocess instance. A reference to the sending subprocess is also available as the second argument in the ipc handler.

const childProc = Bun.spawn(["bun", "child.ts"], {
  ipc(message, childProc) {
    /**
     * The message received from the sub process
     **/
    childProc.send("Respond to child");
  },
});

childProc.send("I am your father"); // The parent can send messages to the child as well

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Meanwhile the child process can send messages to its parent using with process.send() and receive messages with process.on("message"). This is the same API used for child_process.fork() in Node.js.

process.send("Hello from child as string");
process.send({ message: "Hello from child as object" });

process.on("message", message => {
  // print message from parent
  console.log(message);
});

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All messages are serialized using the JSC serialize API, which allows for the same set of transferrable types supported by postMessage and structuredClone, including strings, typed arrays, streams, and objects.

// send a string
process.send("Hello from child as string");

// send an object
process.send({ message: "Hello from child as object" });

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See Docs > API > Child processes for complete documentation.