Mac Apps That Use Garbage Collection Must Move to ARC

[Andrei Alexandrescu via Digitalmars-d]

On 2/21/15 12:22 PM, deadalnix wrote:
> On Saturday, 21 February 2015 at 19:20:48 UTC, JN wrote:
>> https://developer.apple.com/news/?id=02202015a
>>
>> Interesting...
>>
>> Apple is dropping GC in favor of automatic reference counting. What
>> are the benefits of ARC over GC? Is it just about predictability of
>> resource freeing? Would ARC make sense in D?
>
> Apple never was able to roll out a good GC for ObjC and got back to ARC
> (an overly complex reference counting system that the compiler is aware
> of).
>
> You get the usual tradeof of RC vs GC :
>   - RC is more predictable.
>   - RC has less floating garbage, so usually a lower memory foot print.
>   - RC usually increase cache pressure as you need to have reference
> count ready and hot.
>   - RC behave (very) poorly when reference are shared across cores, as
> they ill compete for cache lines. It tends to be faster in single
> threaded mode, but that depends on the type of application (graph
> manipulation for instance, tend to behave poorly with RC).
>   - RC can leak.
>   - RC is unsafe without ownership.

Apparently Apple has delivered on a well oiled RC implementation and has 
"won". Most people who develop for both iOS and Android prefer the 
former. -- Andrei