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Help with IPC and child_process with ES6 #1383
Description
- 8.11.2 & 10.6
- Linux, debian x86_64
- runtime
- child_process
IPC with a ES6 child process created via child_process.fork() appears to go nowhere. When sending a message, the child appears to never receive it. Further testing shows that other events (eg exit) are working.
To demonstrate, parent.mjs:
import cp from 'child_process';
const kid = cp.fork( 'test.mjs' );
kid.send( { msg: "Hey there kid" } );
setTimeout( () => { process.exit(0) }, 2000 ); And test.mjs
class Test {
constructor() { }
msg(message) { console.log( "Kid got", message ); }
}
const test = new Test();
process.on( 'message', (m) => { test.msg(m) } );To test further, I created my own named socket IPC using net.createServer(path), between such a parent and child, and bidirectional communication is working.
I really just want to know if this is something I should create an issue about.
Activity
vsemozhetbyt commentedon Jul 12, 2018
cc @nodejs/child_process @nodejs/modules-active-members
benjamingr commentedon Jul 12, 2018
Can you try putting the
.sendin asetTimeout? I think you're calling.sendsynchronously before the child process has run theprocess.on( 'message', (m) => { test.msg(m) } );code.bmeck commentedon Jul 12, 2018
in general you can see dropped messages due to timing like @benjamingr said, it is a much more foolproof workflow to have your child notify the parent that it is fully loaded before sending it messages from the parent.
sammyrc34 commentedon Jul 12, 2018
@benjamingr Thank you! You're correct.
@bmeck, yes, that is a much better approach.
Thank you both for the help.