process.title behaves different on linux with node >= 12.17 from other platform

[yaodingyd]

• Version: 12.17
• Platform: Linux 14.04.1-Ubuntu x86_64 GNU/Linux
• Subsystem: process

What steps will reproduce the bug?

I have this following script to spin up a noop process

const childProcess = require('child_process')

const code = `
	process.title = 'noop-process';
	setInterval(() => {}, 1000 * 1000);
	console.log('ok');
`;

const subprocess = childProcess.spawn('node', ['-e', code], {
	detached: true
});

console.log(subprocess.pid)

Then run ps -p pid -o comm

On linux node > 12.17, the COMMAND shows 'node', where on MAC node with any version or linux with node <=12.16 gives COMMAND noop-process

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior?

It should always show COMMAND is "noop-process"

What do you see instead?

Additional information

[mmomtchev]

There are two "process titles" in Linux

• one is the so-called command line that you see when you do ps uaxw, it comes from /proc/<pid>/cmdline and this one is still modified by process.title
• the other one is the thread name that you see when you do ps -p <pid>, that one comes from /proc/<pid>/comm and it was broken by libuv 1.35.0 that was added in Node 12.17

This is the commit that broke it: libuv/libuv@7b28d36#diff-061ff4a1f558b9316c85e332cfe90b66b3b5b612455249bfc1bb19a24e7f28e1 , line 101

[somnathpanja]

Still the issue exist with normal node main process itself for version >= v12.17.0

Node: v12.20.0
OS: Ubuntu 16.04 lts

timer.js

process.title = "Foo";

var timer = function() {
    setTimeout(() => {
        let k = 0;
        for(i=0; i<40000;i++){
          k += 10;
        }
        timer();
    }, 1000);
};

timer();

> node timer.js

Running TOP Command

[santigimeno]

This was already fixed in libuv v1.41.0