Re: Some experience with the igc branch

[Gerd Möllmann]

Pip Cet <pipcet@protonmail.com> writes:

> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>
>> New day, new beliefs :-). Today, when I read my question again, I'd
>> actually be surprised if a signal handler could allocate Lisp objects
>> because I wouldn't be able to explain how that works with alloc.c which
>> isn't reentrant. Not even Fcons is reentrant when I look at it now.
>>
>> Correct, or am I overlooking something? Could others please check? If
>> it's right, things get a lot easier.
>
> I agree.  But Eli said something about wanting to run Lisp from a signal
> handler, which would change that.  I was trying to explain why we don't
> want to do that.

Thanks for checking! Must be kind of a misunderstanding going on. And
anyway, it would be a feature we don't have with the old GC, so I'd
declare it out of scope :-).

>> Maybe allocation of Lisp objects on the stack remains as some sort of
>> problem (AUTO_CONS etc)? I don't see how though, ATM.
>
> Stack objects are always optional, so if there is code that attempts to
> avoid alloc.c by using those, it's broken.

Yes!

> My current patch makes it so the main thread never takes the arena lock,
> ever.  

Hm, how and why does that work?