What keeps my process open?

open-handles.js

var setInterval = require('timers').setInterval;

setInterval(function () {
  var handles = process._getActiveHandles();
  
  console.log('no of handles', handles.length);
  handles.forEach(function (obj) {
    if ('ontimeout' in obj) {
      console.log('timer handle', obj);
    } else if ('readable' in obj && 'writable' in obj) {
      // to debug stream handles print the _events functions
      // to string and figure out what kind of stream they are
      // then stare really hard at the source code
      // console.log(obj._events.end.toString());
      console.log('stream handle', obj);
    } else {
      console.log('unknown handle', obj);
    }
  })
}, 5000).unref();

obj.owner is the owning "public" object, e.g. the encapsulating net.Socket for a TCP handle.

Doesn't work for regular timers because they sit in a queue backed by a single timer handle but it does work for timers that have been unref()'d; those get moved out of the queue and assigned individual timer handles.