pthread_join always causes SIGSEGV - c

Question

For some reason, pthread_join always causes a SIGSEGV action on my computer when I run with Valgrind. To test this, I ran the following code from https://computing.llnl.gov/tutorials/pthreads/:
/* pthread.c */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define NUM_THREADS 4
void *BusyWork(void *t)
{
int i;
long tid;
double result=0.0;
tid = (long)t;
printf("Thread %ld starting...\n",tid);
for (i=0; i<1000000; i++)
{
result = result + sin(i) * tan(i);
}
printf("Thread %ld done. Result = %e\n",tid, result);
pthread_exit((void*) t);
}
int main (int argc, char *argv[])
{
pthread_t thread[NUM_THREADS];
pthread_attr_t attr;
int rc;
long t;
void *status;
/* Initialize and set thread detached attribute */
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
for(t=0; t<NUM_THREADS; t++) {
printf("Main: creating thread %ld\n", t);
rc = pthread_create(&thread[t], &attr, BusyWork, (void *)t);
if (rc) {
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
}
/* Free attribute and wait for the other threads */
pthread_attr_destroy(&attr);
for(t=0; t<NUM_THREADS; t++) {
rc = pthread_join(thread[t], &status);
if (rc) {
printf("ERROR; return code from pthread_join() is %d\n", rc);
exit(-1);
}
printf("Main: completed join with thread %ld having a status of %ld\n",
t,(long)status);
}
printf("Main: program completed. Exiting.\n");
pthread_exit(NULL);
}
Running
$ clang -g -o pthread pthread.c
$ valgrind --leak-check=full ./pthread
Yields the following valgrind error:
==17283== Process terminating with default action of signal 11 (SIGSEGV)
==17283== Access not within mapped region at address 0x700002F3CC3E
==17283== at 0x10044437F: _pthread_find_thread (in /usr/lib/system/libsystem_pthread.dylib)
==17283== by 0x100446D52: _pthread_join_cleanup (in /usr/lib/system/libsystem_pthread.dylib)
==17283== by 0x100446C63: pthread_join (in /usr/lib/system/libsystem_pthread.dylib)
==17283== by 0x100000D52: main (pthread.c:50)
My Computer is a Mac OS X (El Capitan). For clang, I am using Apple LLVM version 7.0.2 (clang-700.1.81). For Valgrind I am using valgrind-3.11.0.

Answer 1

I was unable to reproduce your problem on my Mac OS X Yosemite (10.10.5) with kernel 14.5.0. The Clang and Valgrind versions I use are the same as yours (please double check just in case):
$ clang --version
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin14.5.0
Thread model: posix
$ valgrind --version
valgrind-3.11.0
Thus the only difference is the OS version. Here are the steps I followed:
Refreshed the installation of the developer tools by running
xcode-select --install. Without doing this I could not build
Valgrind.
Set the CC and CXX environment variables to clangand
clang++, respectively. I did this to ensure that Clang, not GCC,
is used. Setting CXX was probably overkill. I later wiped out the Valgrind installation and re-did it
with GCC, but it was still a success, even though I think I was
getting more warnings.
Did ./configure --prefix=/usr/local in the root of the untarred
Valgrind tarball, followed by make and sudo make install.
Hopefully these steps help you resolve the issue.