Node.js get open file descriptor count (development)

Question

I'm using chokidar to watch files, and I get EMFILE errors, and I know that this happened because I have too many file descriptors currently open.

I'm using socket, so graceful-fs doesn't fix the problem. Also, setting my ulimit temporarily is, well, temporary.

Is there a way to get the number of file descriptors currently open in code? I want to check if the number is about to go over limit, and make the process wait before it continues watching files/directories.

Answer 1

A simple way to get the current open fd count (assuming you have a /proc fs) is to check the number of entries in /proc/self/fd:

var readdir = require('fs').readdir;

readdir('/proc/self/fd', function(err, list) {
  if (err) throw err;
  console.log(list.length);
});

Keep in mind, opening the directory for reading will incur another open fd.

If you want to check the number of open file descriptors from an external process, just replace self with the pid you want to check.