When Profiling Javascript in Chrome how do I know I've handled Memory Leaks?

Question

I've been working on a game in for HTML 5 using the canvas tag, and I've build up quite a code base to cover my requirements. I also want to make sure I'm covering up all my memory leaks.

I have doubts I'm doing it correctly because the feedback I'm getting from Chrome's task manager and profiling tools seem to suggest my cleanup is having no effect in the end.

Here's an image so you can see what I mean:

So as you can see, once I do my cleanup memory usage just freezes and doesn't drop. Is this a memory leak?

When I ran my webpage in the Profiler and checked the heap before and after cleanup it does appear to remove all the references to my objects (and they disappear) but my usage only drops by only a few kilobytes leaving about 1.3mb of arrays, strings, and other objects behind. Is it impossible to catch all this or is there something majorly wrong?

Thanks.

Answer 1

At the bottom of the profiler window there is an icon that looks like a trash can, it will force a GC pass.

Hit it and see if it clears up the rest of the memory.

It's possible Chrome/V8 just doesn't think the memory situation is bad enough to require garbage collection to run.

Answer 2

Try chrome://memory-redirect/ (or about:memory, both go to the same place). It'll show you the exact amount of memory being used by each tab/etc, plus the memory used by tags/etc in IE, Opera, Firefox, etc. if you have those open at the same time. The raw numbers should be a little more helpful than just the graph at profiling your memory use for potential leaks.

Answer 3

You can compare two heap snapshots and see the delta. You can also directly look at the memory snapshot: https://developers.google.com/chrome-developer-tools/docs/heap-profiling-comparison?hl=pt-PT