Home/ Questions/Q 7858109
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-02T21:16:26+00:00

I am learning to create shared libraries in Linux, subsequently to develop parallelised scientific

  • 0

I am learning to create shared libraries in Linux, subsequently to develop parallelised scientific computing programs. I took the toy example from here for shared library. I modified the Makefile from this question to suit the toy example. My Makefile now is

CC        = mpicc

INCDIR    = -I ./

CFLAGS    = -Wall -rdynamic -g -fPIC $(INCDIR)

LIBADD    = -L ./ -lcalc_mean

all: dyn_main.out

dyn_main.out: libcalc_mean.so
    $(CC) -o $@ main.c $(LIBADD)

libcalc_mean.so:    calc_mean.o
    $(CC) -shared --export-dynamic -o $@ $<

calc_mean.o: calc_mean.c
    $(CC) $(CFLAGS) -c $<

clean :
    -rm *.o
    -rm *.out
    -rm *.so

.PHONY:
    clean

When I make with CC = gcc in the Makefile, things run fine. I could run the binary even with mpirun.

When I have CC = mpicc in the Makefile, I get the following error.

mpicc -Wall -rdynamic -g -fPIC -I ./ -c calc_mean.c
mpicc -shared --export-dynamic -o libcalc_mean.so calc_mean.o
mpicc -o dyn_main.out main.c -L ./ -lcalc_mean
/home/elan/localinstalls/lib/libmpi.so: undefined reference to `pthread_key_create'
/home/elan/localinstalls/lib/libmpi.so: undefined reference to `pthread_getspecific'
/home/elan/localinstalls/lib/libmpi.so: undefined reference to `pthread_create'
/home/elan/localinstalls/lib/libmpi.so: undefined reference to `pthread_atfork'
/home/elan/localinstalls/lib/libmpi.so: undefined reference to `pthread_setspecific'
/home/elan/localinstalls/lib/libmpi.so: undefined reference to `pthread_join'
collect2: ld returned 1 exit status
make: *** [dyn_main.out] Error 1

I added the path to libpthread.so,.a to LD_LIBRARY_PATH, but no avail. I have a self compiled openmpi-1.5.4. If this were a openmpi dependency, shouldn’t it have been resolved when I configured it?

Is this error familiar? I am using Ubuntu 11.04, with gcc 4.5.2. I already built and run some mpi parallel programs successfully. But they are large packages configured with autotools. One of the config.log s display the same error. But even that one runs fine.

References to / examples of creating static/shared libraries with mpi will also be appreciated (though Openmpi discourages fully static libraries.)

Thank you very much,

Elan.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You should be able to just add -lpthread.

    Open MPI probably didn’t add it because it found that adding -lpthread wasn’t necessary (likely due to some other dependency implicitly pulling in the pthread library). But with the linker flags you’re using, you might well have changed that implicit dependency, so the pthread library isn’t being pulled in automatically anymore.

    If adding -lpthread to the command line fixes the issue, then see this FAQ entry for how to update the wrapper compilers (E.g., add your own flags): http://www.open-mpi.org/faq/?category=mpi-apps#override-wrappers-after-v1.0

    • 0