From: Andrew Benson <abensonca@gmail.com>
To: Fortran <fortran@gcc.gnu.org>
Subject: gfortran, OpenMP and static linking
Date: Fri, 16 Sep 2022 15:51:00 -0700 [thread overview]
Message-ID: <1720594.qhh6PHbjeT@abensonca-precision-7540> (raw)
I've been following the fix proposed by Bernhard in this thread:
https://gcc.gnu.org/pipermail/fortran/2021-April/055907.html
to allow static linking of Fortran codes compiled with -fopenmp. (I know that
static linking of OpenMP codes isn't guaranteed to work, but this fix has
worked well for me anyway.)
This fix seems to no longer work with glibc >= 2.34 - I think because the
functionality of libpthread has been integrated into libc:
https://sourceware.org/pipermail/libc-alpha/2021-August/129718.html
When compiling the simple test code from that thread with glibc 2.34 or newer
I get a segfault:
$ cat omp.f90
use omp_lib
!$omp parallel
write(*,*) "thread ", omp_get_thread_num()
!$omp end parallel
end
$ gfortran -o omp -fopenmp omp.f90 -static -Wl,--whole-archive -lpthread -
Wl,--no-whole-archive && OMP_NUM_THREADS=2 ./omp
./../../gcc-13-source/gcc-13-20220710/libgomp/config/linux/../../allocator.c:
102: warning: Using 'dlopen' in statically linked applications requires at
runtime the shared libraries from the glibc version used for linking
./../../gcc-13-source/gcc-13-20220710/libgomp/oacc-profiling.c:137: warning:
Using 'dlopen' in statically linked applications requires at runtime the
shared libraries from the glibc version used for linking
thread 0
thread 1
Program received signal SIGSEGV: Segmentation fault - invalid memory
reference.
Backtrace for this error:
#0 0x467b0f in ???
#1 0x0 in ???
Segmentation fault (core dumped)
Tracking this down in gdb it seems that pthread_mutex_destroy() is called, but
that symbol is null.
From comment #9 in this PR:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58909#c9
I figured out a workaround, which is to create a C file with this content:
#include "pthread.h"
#define nullptr ((void*)0)
void pthread_workaround() {
pthread_mutex_destroy((pthread_mutex_t *) nullptr);
}
which defines a function pthread_workaround() which calls
pthread_mutex_destroy(), but which itself it never called. Compiling that C
code, and linking with the Fortran allows the test code to run successfully.
$ gcc -c -o fix.o -fopenmp fix.c
$ gfortran -c -o omp.o -fopenmp omp.f90
$ gfortran -o omp -fopenmp -static omp.o fix.o
./../../gcc-13-source/gcc-13-20220710/libgomp/config/linux/../../allocator.c:
102: warning: Using 'dlopen' in statically linked applications requires at
runtime the shared libraries from the glibc version used for linking
./../../gcc-13-source/gcc-13-20220710/libgomp/oacc-profiling.c:137: warning:
Using 'dlopen' in statically linked applications requires at runtime the
shared libraries from the glibc version used for linking
$ OMP_NUM_THREADS=2 ./omp
thread 0
thread 1
My understanding of glibc, pthreads, etc. etc. is insufficient to know if this
is a good and/or safe workaround, but I figured I'd share it here in case:
a) it's useful to anyone;
b) it's indicative of a bug in gfortran;
c) anyone has a more elegant solution!
-Andrew
--
* Andrew Benson: https://abensonca.github.io
* Galacticus: https://bitbucket.org/abensonca/galacticus
next reply other threads:[~2022-09-16 22:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 22:51 Andrew Benson [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-04-03 18:55 Harald Anlauf
2021-04-03 21:24 ` Bernhard Reutner-Fischer
2021-04-04 10:46 ` Bernhard Reutner-Fischer
2021-04-04 20:17 ` Harald Anlauf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1720594.qhh6PHbjeT@abensonca-precision-7540 \
--to=abensonca@gmail.com \
--cc=fortran@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).