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bug#69706: 30.0.50; sort.c, unnecessary GC marking
From: |
Gerd Möllmann |
Subject: |
bug#69706: 30.0.50; sort.c, unnecessary GC marking |
Date: |
Sun, 10 Mar 2024 15:01:59 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
Mattias Engdegård <mattias.engdegard@gmail.com> writes:
> 10 mars 2024 kl. 12.29 skrev Gerd Möllmann <gerd.moellmann@gmail.com>:
>
>> You nean sort.c is removing objects temporarily from the vector, so that
>> they are not reachable from any other root, especially from the control
>> stack? Could be, the code is a bit hard to follow.
>
> The comment in cleanup_mem is explicit about this:
Ok, too bad :-(
>
>> /* If we have an exception while merging, some of the list elements
>> might only live in temp storage; we copy everything remaining in
>> the temp storage back into the original list. This ensures that
>> the original list has all of the original elements, although
>> their order is unpredictable. */
>
>
>> Please make it easy for a concurrent, mostly-copying GC, use the stack
>
> We can't use the C stack for allocations of arbitrary size,
> unfortunately.
That goes without saying. I was more thinking about having a Lisp_Vector
on the stack, maybe in the state, which is already on the stack.
> Furthermore, we currently make the (correct) assumption that explicit
> xmalloc/xfree for temporary storage is faster than allocating a Lisp
> vector in most places. If a new GC shrinks the performance gap
> sufficiently, then we could reconsider that.
>
> See bug#69709 for the new `sort` plan.
Thanks, if I find the time, I'll take a look.
So, I guess I should close this.