Node.js process ignores the max open files soft limit

[ocodista]

Version

v21.4.0

Platform

Linux ip-10-0-1-185 6.2.0-1012-aws #12~22.04.1-Ubuntu SMP Thu Sep 7 14:01:24 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

No response

What steps will reproduce the bug?

node -e "console.log('Current PID:', process.pid); require('child_process').exec('cat /proc/' + process.pid + '/limits', (err, stdout) => { if (err) throw err; console.log(stdout); });"

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

Always.

What is the expected behavior? Why is that the expected behavior?

It should respect the Soft Limit of Max Open files, but it is not, it is ignoring it.

What do you see instead?

ubuntu@ip-10-0-1-185:~/node-api$ ulimit -n
1024
ubuntu@ip-10-0-1-185:~/node-api$ node -e "console.log('Current PID:', process.pid); require('child_process').exec('cat /proc/' + process.pid + '/limits', (err, stdout) => { if (err) throw err; console.log(stdout); });"
Current PID: 3133
Limit                     Soft Limit           Hard Limit           Units
Max cpu time              unlimited            unlimited            seconds
Max file size             unlimited            unlimited            bytes
Max data size             unlimited            unlimited            bytes
Max stack size            8388608              unlimited            bytes
Max core file size        0                    unlimited            bytes
Max resident set          unlimited            unlimited            bytes
Max processes             3738                 3738                 processes
Max open files            1048576              1048576              files
Max locked memory         124477440            124477440            bytes
Max address space         unlimited            unlimited            bytes
Max file locks            unlimited            unlimited            locks
Max pending signals       3738                 3738                 signals
Max msgqueue size         819200               819200               bytes
Max nice priority         0                    0
Max realtime priority     0                    0
Max realtime timeout      unlimited            unlimited            us

Additional information

No response

[H4ad]

Initially, I thought it was something related to libuv, but libuv/libuv#3181 points to 6820054d2d.

@bnoordhuis Why node raises the softLimit?

[targos]

The commit message of 6820054d2d explains it.
The soft limit on macOS is 256 by default.

[bnoordhuis]

It's higher nowadays but still too low for many practical purposes. Intentional behavior, not a bug. Closing.