Creating multiple threads and invoking other exectuables in Cygwin through system()?

Question

I am working on a project in Cygwin. In an attempt to create multiple threads in C, and each thread calls another executable through the command line using the system() function, it turns out things are not working properly. Specifically, the code I have is like this:

#include <pthread.h>
#include <stdio.h>
#define NUM_THREADS     5

void *PrintHello(void *threadid)
{
long tid;
tid = (long)threadid;
system("date ");
pthread_exit(NULL);
}

int main (int argc, char *argv[])
{
pthread_t threads[NUM_THREADS];
int rc;
long t;

for(t=0; t<NUM_THREADS; t++){
  printf("In main: creating thread %ld\n", t);
  rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
  if (rc){
     printf("ERROR; return code from pthread_create() is %d\n", rc);
     exit(-1);
  }
}
pthread_exit(NULL);

}

But it does not work. The error I get is segmenetation fault with stack overflows. Anyway has an idea on how to call other executables in the system shell in parallel by creating multiple threads? Thanks.

Answer 1

That issue looks worth reporting to the Cygwin mailing list.

What you can do instead is to do away with threads and use fork()/exec() or spawn(_P_NOWAITO, ...) to create the child processes.

(spawn() actually is a family of functions; see /usr/include/process.h for details. Its use is recommended as it avoids Cygwin's high fork overhead.)