Re: MPS: weak hash tables

[Gerd Möllmann]

Pip Cet <pipcet@protonmail.com> writes:

>> The big
>> difference to the non-MPS case is that struct interval is subject to GC
>> at all, they are malloc'd without igc. I didn't see another way to
>> handle their plist otherwise. Making them malloc'd roots would have
>> meant too many roots for my taste. I have currently ca. 20.000 live
>> intervals for example, after GC.
>
> Does there have to be a big difference at all, 

The only thing i can think of is what Helmut already suspected, namely
barriers. OTOH, it's not really noticeable in other cases, at least here
on macOS. In any case, I wouldn't expect anything remotely that big.
After all, it's not like a barrier is hit, the client runs a bit, and
the barrier goes up again.

> or is it possible the test is broken on vanilla Emacs, and it just so
> happens that GC happens at the right time and hides that bug?

ERT is a dark chapter for me. Digged through it once for the debugger
handling and giving the right backtraces in condition-case, and didn't
like it :-). I'd say everything is possible.

> The attached patch to Emacs master makes
>
> make -C test lisp/emacs-lisp/ert-tests
>
> run out of memory for me (again, on master, nothing special). I don't
> think it should: all it does is modify the test that runs before.
>
> So is it possible this isn't all that MPS-specific?

I have to admit I don't understand how that has the effect it has. Can
you see where it gets stuck?