nodejs setTimeout memory leak?

Question

v0.10.4

Here\'s the simple loop that results in an ever-increasing memory usage:

function redx(){
      setTimeout(function(){ redx() },1000);
      cons         


        

Answer 1

Actually, I think it might be just the way the V8 garbage collector works.

On my system, node heap tends to increase up to 48 MB and then stabilize, so I think if you keep your program running for a long time, the memory consumption will eventually stabilize.

You can have information about when/how the GC kicks in by launching node with one of the V8 command line option: the --trace_gc flag.

In your first tries with Redis, you were systematically connecting/disconnecting from Redis at each call. This tends to generate garbage. You are supposed to open a connection once and use it many times. Nevertheless, even when I do this, memory consumption tends to stabilize. Here is the evolution of memory consumption on this example with Redis:

// something close to your initial function (when Redis was still in the picture)
function redx(){
    var client = redis.createClient();
    client.get("tally", function(err, reply) {
        client.quit();
    });
    setTimeout(function(){ redx() }, 50 );
}

Here, the stabilization after 60 MB seems to be quite obvious.

Answer 2

No idea why but apparently if you reference the timeout object in the scope of the function nodejs will do the garbage collect that correctly.

function redx(){
      var t = setTimeout(function(){ redx() },50);
      console.log('hi');
}

redx();