reducing the contention in dl_iterate_phdr (reloaded)

reducing the contention in dl_iterate_phdr (reloaded)

[Vincenzo Innocente]

I found this old thread about lack of concurrency in  dl_iterate_phdr that affects gcc unwinding.
https://sourceware.org/pipermail/libc-help/2020-May/005275.html

I discover this issue while experimenting with C++23 std::stacktrace in a multithread application.

Has been made any progress on the subject since May 2020?


   cheers,
Vincenzo Innocente

Re: reducing the contention in dl_iterate_phdr (reloaded)

[Adhemerval Zanella Netto]

On 22/11/23 08:13, Vincenzo Innocente via Libc-help wrote:
> I found this old thread about lack of concurrency in  dl_iterate_phdr that affects gcc unwinding.
> https://sourceware.org/pipermail/libc-help/2020-May/005275.html
> 
> I discover this issue while experimenting with C++23 std::stacktrace in a multithread application.
> 
> Has been made any progress on the subject since May 2020?

Starting with version 2.35, glibc provides _dl_find_object [1] which is
used by libgcc unwinder [2] functions to fix the scalability issues. 
The libstdc++ must be built against a glibc 2.35 headers to enable it.

[1] https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586170.html
[2] https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg273082.html