low-latency GC

[Bruce Carneal]

On Sunday, 6 December 2020 at 06:52:41 UTC, Ola Fosheim Grostad 
wrote:
> On Sunday, 6 December 2020 at 05:41:05 UTC, Bruce Carneal wrote:
>> OK.  Some rationale?  Do you, for example, believe that 
>> no-probable-dlanger could benefit from a low-latency GC?  That 
>> it is too hard to implement?  That the language is somehow 
>> incompatible? That ...
>
> The GC needs to scan all the affected call stacks before it can 
> do incremental collection. Multi threaded GC is generally not 
> compatible with low level programming.

GCs scan memory, sure.  Lots of variations.  Not germane.  Not a 
rationale.

D is employed at multiple "levels".  Whatever level you call it, 
Go and modern JVMs employ low latency GCs in multi-threaded 
environments.  Some people would like to use D at that "level".

My question remains: how difficult would it be to bring such 
technology to D as a GC option?  Is it precluded somehow by the 
language?   Is it doable but quite a lot of effort because ...?  
Is it no big deal once you have the GC itself because you only 
need xyz hooks? Is it ...?

Also, I think Walter may have been concerned about read barrier 
overhead but, again, I'm looking for feasibility information.  
What would it take to get something that we could compare?