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Re: dfa MT-safe?
From: |
Bruno Haible |
Subject: |
Re: dfa MT-safe? |
Date: |
Sun, 15 Dec 2019 13:06:22 +0100 |
User-agent: |
KMail/5.1.3 (Linux/4.4.0-166-generic; KDE/5.18.0; x86_64; ; ) |
Arnold Robbins wrote:
> Paul Eggert <address@hidden> wrote:
> > Yes it is supposed to be.
>
> News to me.
:) It's time that we start documenting the multithread-safety of the gnulib
modules. Cf. [1]
> In any case, gawk's use of it is (and will remain) single-threaded.
> It'd be nice if your fix did not pull in more libraries, like libpthread
> or whatever, since that would considerably complicate things for me,
> for no actual gain w.r.t. gawk.
If you add these two lines to configure.ac:
gl_cv_func_setlocale_null_all_mtsafe=yes
gl_cv_func_setlocale_null_one_mtsafe=yes
no additional libraries will be needed.
> I'm curious what is the use case for multithreaded dfa?
One could speed up
grep -r PATTERN DIRECTORY_WITH_MANY_FILES
by a large factor (probably 4x or 5x, on a CPU with 8 threads).
This would be done by modifying 'grep' to process each file in a
separate thread. The kernel can feed the data of these files to 'grep'
in parallel. Only the output phase needs to serialize things.
José Marchesi suggested this, a couple of months ago.
Bruno
[1] https://lists.gnu.org/archive/html/bug-gnulib/2019-12/msg00002.html