Example: Waiting for threads in a Pthread program

This example shows a Pthread program starting several threads, waiting for them to finish, and checking their status after they are completed.

Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.

/*
Filename: ATEST13.QCSRC
The output of this example is as follows:
 Enter Testcase - LIBRARY/ATEST15
 Create/start some worker threads
 Thread 00000000 000001a4: Entered
 Thread 00000000 000001a4: Working
 Wait for worker threads to complete, release their resources
 Thread 00000000 000001a8: Entered
 Thread 00000000 000001a8: Working
 Thread 00000000 000001a5: Entered
 Thread 00000000 000001a5: Working
 Thread 00000000 000001a6: Entered
 Thread 00000000 000001a6: Working
 Thread 00000000 000001a7: Entered
 Thread 00000000 000001a7: Working
 Thread 00000000 000001a4: Done with work
 Thread 00000000 000001a8: Done with work
 Thread 00000000 000001a6: Done with work
 Thread 00000000 000001a7: Done with work
 Thread 00000000 000001a5: Done with work
 Check all thread's results
 Main completed
*/
#define _MULTI_THREADED
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define THREADGROUPSIZE   5
 
#define checkResults(string, val) {             \
 if (val) {                                     \
   printf("Failed with %d at %s", val, string); \
   exit(1);                                     \
 }                                              \
}
 
void *theThread(void *parm)
{
   printf("Thread %.8x %.8x: Entered\n", pthread_getthreadid_np());
   printf("Thread %.8x %.8x: Working\n", pthread_getthreadid_np());
   sleep(15);
   printf("Thread %.8x %.8x: Done with work\n", pthread_getthreadid_np());
   return NULL;
}
 
int main(int argc, char **argv)
{
  pthread_t             thread[THREADGROUPSIZE];
  void                 *status[THREADGROUPSIZE];
  int                   i;
  int                   rc=0;
 
  printf("Enter Testcase - %s\n", argv[0]);
 
  printf("Create/start some worker threads\n");
  for (i=0; i <THREADGROUPSIZE; ++i)
 {
    rc = pthread_create(&thread[i], NULL, theThread, NULL);
    checkResults("pthread_create()\n", rc);
  }
 
  printf("Wait for worker threads to complete, release their resources\n");
  for (i=0; i <THREADGROUPSIZE; ++i) {
rc = pthread_join(thread[i], &status[i]);
    checkResults("pthread_join()\n", rc);
  }
 
  printf("Check all thread's results\n");
  for (i=0; i <THREADGROUPSIZE; ++i) {
if (status[i] != NULL) {
      printf("Unexpected thread status\n");
    }
  }
 
  printf("Main completed\n");
  return 0;
}