Why does an empty node.js script consume more and more RAM?

Question

Why does an empty node.js script consume more and more RAM?

Running this:

setInterval(function() {
    console.log(process.memoryUsage());
}, 1000);

shows memory usage constantly growing:

{ rss: 9076736, heapTotal: 6131200, heapUsed: 2052352 }
... some time later
{ rss: 10960896, heapTotal: 6131200, heapUsed: 2939096 }
... some time later
{ rss: 11177984, heapTotal: 6131200, heapUsed: 3141576 }

Why does this happen?

node.js
memory-leaks

Answer 1

The program isn't empty, it's running a timer, checking memory usage, and writing to the console once a second. That causes objects to be created in the heap and until garbage collection runs your heap usage will keep increasing.

If you let it go you should eventually see heapUsed go back down each time garbage collection is triggered.