Saagar JhaI get the feeling that the “ARC is great because you don’t have to deal with garbage collection pauses!!!” people have never had to close a 20 GB Instruments trace
“But it’s deterministic when the deallocations happen!” yeah I can see that clicking the red x made the app hang for 30 seconds, cool. In a generational GC I would have surely been mystified what caused the pause 10ms after I closed the document
(Actually I would expect that the garbage collection pass would bail out before long and reschedule the remaining work for the next pause, whereas ARC basically requires deallocation to occur now…)
Pierre H.@saagar GC uses more memory, and using more memory is just a loan on memory you don’t have on a phone.
I despise GCS. (Sorry Miguel).
At the end of the day you use refcount only if you have shared references (and hopefully swift will grow increasingly better at understanding borrows)
@madcoder My scalding hot take for today is that “we don’t have enough memory for a GC on a phone” is a boomer Apple engineer opinion from the 2010s
@saagar you’re entitled to your incorrect opinions :p
For an app maybe. For the system, absolutely not
@madcoder The part I left out because I figured it would make you more upset was “everyone shipping JavaScript apps these days is going to make the decision for you anyways whether you like it or not”
@saagar ouch. You had to go there.
@saagar but I did carve out the “for apps”. There are an order of magnitude (or more) more processes than apps on a typical system (electron apps don’t count here, they have too many processes themselves and are an abomination, fortunately, not on phones).
A GC on the system by default would cost you a lot. Way more than we deem acceptable.
@madcoder (Simmering down a bit, but still warm take) You’re not trying hard enough, Android shows what you can get when you train your shared cache engineers towards how to amortize garbage collectors
@madcoder If you control the entire language btw you can ensure that most things don’t even become garbage in the first place
@saagar it’s even worse with JS because you also pay the JIT tax (code is dirty memory and not shared, one of the reasons I absolutely dislike Java)
@madcoder Once again, you aren’t thinking hard enough ;) You can AOT compile most of the system image and map it across multiple processes
@madcoder Code pages for a specific app are of course not shared but you’re falling back to a binary for all cold paths anyways, so the actual live set of dirty pages that are not from disk can be tuned to be pretty small