Missing IPC chanel

[arthot]

Hi, I've noticed yet another problem with a spawn of child process.
For now ts-node has the following option while creating a child node: stdio: 'inherit'.
And according node.js docs it means "no IPC" (Inter-process communication)

In reality this breaks a communication with yet another parent:

parent.js:

const cp = require('child_process');
cp.fork('child.ts', [], {
        env: process.env,
        execPath: 'node_modules/.bin/ts-node'
    });

child.ts:

if (!process.send)
    console.log('IPC is not enabled');
else
    console.log('IPC is enabled')

will produce IPC is not enabled

See more details in the sample repository with proper environment.

So I propose to replace the stdio option value with ['inherit', 'inherit', 'inherit', 'ipc'] in order to enable IPC. I think it's quite safe change because according the stdio doc

the child is launched with the IPC channel unreferenced until the child registers an event handler for the process

After such modification the sample will produce IPC is enabled

If someone is wondering about real-life use case sample:

1. npm start
2. webpack build client source
3. run server api + webpack dev server
4. wait until the server will start
5. open browser

In this chain wait until the server will start is usually implemented in IPC way like process.send('online') and ts-node breaks this for now

PR #502

[blakeembrey]

Thanks for the awesome writeup! I think I'll just kill child processes instead, the amount of hacks are becoming unmanageable and recommending node -r ts-node/register seems more ideal for advanced usage. Thanks!

[arthot]

Yep, if you have plans to remove child process in near future you can close this issue, because

cp.fork('child.ts', [], {
    env: process.env,
    execArgv: ['-r', 'ts-node/register']
});

also produces IPC is enabled

[blakeembrey]

Closing with #536. Thanks for your patience!