Subprocess pid is always 0 about child_process

[mathieudutour]

Ah right, thanks for the nice bug report!

A potential fix would be to use a getter instead of assigning the value directly. Want to send a PR?

[halffullheart]

Yes, I would be happy to try to put together a fix. Can you help me understand why setImmediate() is being used?

From what I can tell, the node API returns a subprocess with the correct PID synchronously, e.g. this works:

const { spawn } = require('child_process')
console.log(spawn('ls').pid) // => non-zero number

Using a getter to call processIdentifier() would still return 0 in a case like this, right?

[mathieudutour]

Hum you're right. Tbh I can't remember why I wrapped it in a setImmediate.
I'm guessing it had to do with making sure the callback is called at the end of the event loop. But maybe it's not necessary

[anyab5]

Another problem with using setImmediate is that exceptions such as :
{ Error: An Obj-C exception occurred. at [native code] (/) at spawn ..... nativeException: <NSException> Couldn't posix_spawn: error 7, line: 817, column: 16
will not get caught in the general catch flow and error will not get triggered.
From client perspective we cannot know when and what exception occurred.
I created a PR for removing setImmediate if that sounds reasonable to you.

[mathieudutour]

fixed in 0.4.2