Concurrent GC (for Windows)

[Rainer Schuetze via Digitalmars-d]

On 04.06.2014 07:44, Benjamin Thaut wrote:
> Am 03.06.2014 09:35, schrieb Rainer Schuetze:
>> Hi,
>>
>> more GC talk: the last couple of days, I've been experimenting with
>> implementing a concurrent GC on Windows inspired by Leandros CDGC.
>> Here's a report on my experiments:
>>
>> http://rainers.github.io/visuald/druntime/concurrentgc.html
>>
>> tl;dr: there is a working(?) partially concurrent GC here:
>> https://github.com/rainers/druntime/tree/concurrent_gc2
>> but it eats a whole lot of memory.
>>
>> Rainer
>
> This sounds quite promising.
>
> Did you think about using a write barrier instead of doing the chech per
> page? Because the way you propose will mean, that all writes, no matter
> if relevant for the GC or not, will cause the GC to reconsider the page.
> If we implement a write barrier into the front end that only gets called
> when a write through a pointer to a pointer happens, the GC could only
> rescan memory blocks that actually have changed pointers. Also the GC
> might be able to remember the old pointer value before the write is
> execued resulting in a consitent snapshot of the heap, which would
> eliminate the need to rescan after the background thread is finished.
>

Yes, write barriers are a good addition to this, but is way more 
difficult to implement and will meet more resistance from Walter. It's 
still something I'd like to look into.