Nodejs garbage collection trigger snippet, work with --expose-gc

garbageCollection.js

/*
  This snippet can help your node automatically trigger garbage collection.
  You have to add V8 flag "--expose-gc" when you start your app.
  
  usage example: (triggerMemorySize - MB, triggerInterval - Seconds, startInvervalDelay - Seconds)
    require('/utils/garbageCollection.js');
    
 or require('/utils/garbageCollection.js')(triggerMemorySize, triggerInterval);
  such as : 
      require('/utils/garbageCollection.js')(150, 60);
 or require('/utils/garbageCollection.js')(triggerMemorySize, triggerInterval, startInvervalDelay);
  such as : 
      require('/utils/garbageCollection.js')(150, 60, 60);
*/

var garbageCollectionInterval = null;

var maximumMemory = 150;  //Trigger garbage collection when memory usage over 150MB
var intervalTime = 60;  //Check memory usage every 60 seconds


module.exports = (function(memorySize, interval, startInvervalDelay) {
  setTimeout(function() {
    if (global.gc) {
      maximumMemory = memorySize || maximumMemory;
      intervalTime = interval || intervalTime;

      if (!garbageCollectionInterval) {
        garbageCollectionInterval = setInterval(function () {
          var currentMemoryUsage = (process.memoryUsage().rss / 1048576).toFixed(2);
          if (currentMemoryUsage > maximumMemory) {
            console.log('[Garbage Collection] > triggered garbage collection, current memory usage: %d MB', currentMemoryUsage);
            global.gc();
          }
        }, intervalTime * 1000).unref();
        console.log('[Garbage Collection] > Automatic garbage collection started, will be triggered when memory bigger than %d MB for every %d seconds.', maximumMemory, intervalTime);
      }

    } else {
      console.error('[Garbage Collection] > Require node argument "--expose-gc", please start your app with this argument.');
    }
  }, startInvervalDelay * 1000);
}());