MemLab: An open source framework for finding JavaScript memory leaks

[mikece]

https://engineering.fb.com/2022/09/12/open-source/memlab/

[emptysea]

Ah I think this was mentioned in a comment on a previous thread:

https://news.ycombinator.com/item?id=29595441

Glad to see it finally open sourced!

[lgong → emptysea]

Yup, that's the previous thread :)

[latchkey]

Memory leak because of console.log? Wow, news to me. Not that I really ever use it for much since I believe in writing unit tests over outputting logs to the console. But I can see how others might get bitten by this for sure.

[chess_buster → latchkey]

Can confirm, have been bitten in production. Therefore we have a lint rule that disallows `console.log` for production builds.

[x-shadowban]

Node heap profiler in chrome is pretty good, often it will show the largest retainers and if your hookes to a live vm (not a snapshot) you can inspect the object and eventually go "oh yeah this array just grows and grows..."

[jalino23]

its incredibly difficult to debug memory leak even with dev tools, I will look into this and hope it helps

[Frotag → jalino23]

I learned recently that Edge has a "Detached Elements" panel that identifies leaked DOM elements and the code / object holding the reference.

It basically automates the process of diff'ing heap snapshots.

[buttersbrian → Frotag]

That's awesome. Thanks for sharing!

[maxloh]

If there is any memory leaks in a garbage-collected language, isn't it a bug of V8 instead?

[astrange → maxloh]

You can just leak memory by leaving references to it around. Sometimes called memory abandonment.

With some systems you can pin it and forget to unpin it.

[fithisux → astrange]

Very good explanation. I always wondered what is the equivalent of memory leak in a garbage collected language. Are there any tools for this?

[astrange → fithisux]

Well, there’s the one in the article. Usually each GC implementation comes with its own tools.

You can watch process memory in general and see if keeps going up; if it does, it’s someone’s fault.

[fithisux → maxloh]

My question exactly.

[darepublic]

The stuff of nightmares