Events from the V8 garbage collector, lets you know when garbage collection occurs.
Just subscribe to events specific to each type of garbage collection ('scavenge' and 'marksweep' for scavenging and mark, sweep and collect respectively):
var nodegc = require('node-gc');
nodegc.on('scavenge', function(info) {
// scavenging just happened
});
nodegc.on('marksweep', function(info) {
// got marked and sweeped
});The passed info object has the following properties:
- duration: How much time was spent collecting. Note that this will in general be slightly higher than what's reported by --trace-gc.
- heapBefore: heap size in bytes before the collection occured.
- heapAfter: heap size in bytes after the collection occured.
The main application of node-gc is to log or graph GC activity. The V8 --trace-gc being just a low-level print, it offers little opportunity for analysis. Plug-in statds and graphite for best effect. You may also want to use it to apply back pressure on memory allocation if that's your thing.
The usual:
npm install node-gc
Test cases use mocha and should. More test cases, patches and pull requests are all welcome. Licensed under the Apache 2.0 license.