More radical ideas about gc and reference counting

[Rainer Schuetze via Digitalmars-d]

On 13.05.2014 14:20, Wyatt wrote:
> On Tuesday, 13 May 2014 at 06:06:40 UTC, Rainer Schuetze wrote:
>>
>> This comes up from time to time, but to me it is very blurry how this
>> can work in reality.
>>
> The paper I linked on Friday [0] presents a collector like this. Are
> there concerns I've missed that make that not applicable?

I just read the first chapters, and according to that, existing local 
gcs needs write barriers, so we are back to my second proposal. The 
implementation in the paper even adds read barriers.

>
>> Considering how "shared" is supposed to be used to be useful (do some
>> locking, then cast away "shared") there is no guarantee by the
>> language that any object is actually thread local (no references from
>> other threads). Working with immutable (e.g. strings) is shared by
>> design.
>
> I'm not seeing much in the documentation, but from what I can tell (per
> the FAQ), shared in D just guarantees it's on the global heap?

To me, shared is a type modifier that doesn't implicitely convert to 
anything else without casting.
If a global/static variable is shared, it is placed into the data 
segment of the executable image, not TLS. The heap is not involved here.


> -Wyatt
>
> [0]
> https://research.microsoft.com/en-us/um/people/simonpj/papers/parallel/local-gc.pdf
>