Nw.js: Spawned child process fails due to stdout & stderr filling up with no way to read from parent

[jobeninc]

Please post a workaround if one is known. Thanks!

NWJS Version : 0.27.4
Node Version : 9.3.0
Operating System : Windows 7

Expected behavior

Message traffic between parent and spawned child should continue uninterrupted

Verified expected behavior with - NWJS Version : 0.19.4, Node Version : 7.2.0

Actual behavior

The spawned child process exits with error code: 3221225477

Sub problems:

• maxBuffer config parameter does not appear to change the buffer size for spawn or fork
• Unable to consume stdout or stderr on the parent side
• The more that spawned processes that leverage third party products that print to stdout, the faster the error occurs

How to reproduce

Run the following code with a helloWorld.html of your choice.

package.json

{ "name": "scratch", "version": "0.0.1", "main": "index.js" }

index.js

`
const path = require('path');
const gui = require('nw.gui');
const spawn = require('child_process').spawn;

gui.Window.open('helloWorld.html', {}, function(win) {});

//Create spawned process
var child = spawn(process.execPath, ['./child.js'], {
stdio: ['pipe', 'pipe', 'pipe', 'ipc'],
execPath: process.execPath
});

//Message sent back from child
child.on('message', function(m) {
console.log('[Child message] ' + m.msg);
});

//Continually send messages to child (simulates typical IPC traffic)
setInterval(function() {
console.log('ping')
child.send('ping');
}, 50);

process.on('uncaughtException', function (err) {
console.error(err);
});
`

child.js

`
//Respond to pings with pongs
process.on('message', function(m) {
setTimeout(function() {
//Add a little bit of print litter to stdout to speed up the errors

process.stdout.write('stdout111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111');
process.send({msg: 'pong'});
});
});
`

[Christywl]

I tried it on Windows 8.1 with nwjs-sdk-v0.27.4, child process stopped and an error occurred:

This doesn't happen on Linux with nwjs-sdk-v0.27.4.

[rowenbuzz]

I am running into the same issue in an application with multiple spawned processes. The application is currently unusable with the same upgrade as the OP. I'm also on Windows 7 as well.

[skaughtx0r]

Not sure if this is related, but I'm using the fork command to spawn a nodejs process and it seems to die immediately on Windows 10 using NW.js 0.27.5.

The only error that prints out is events.js:136 Uncaught NodeError: Channel closed when I try to send a message to the process.

When running with NW.js 0.26.6 it works fine.

[rogerwang]

Yeah this seems to be a regression in 0.27

[rogerwang]

This is fixed in git and will be available in the next nightly build.

[rogerwang]

Please try https://dl.nwjs.io/live-build/nw28/01-31-2018/6d34eb9-c73bf1a-19c0659-668ffc5/v0.28.1/

[skaughtx0r]

Thanks, that 28.1 build appears to be working in my case.

[jobeninc]

That worked for my original issue. Thank you for addressing it so quickly.