pthread_is_multithreaded_np()--Check Current Number of Threads
Syntax:
#include <pthread.h> unsigned int pthread_is_multithreaded_np(void);Service Program Name: QP0WPTHR
Default Public Authority: *USE
Threadsafe: Yes
Signal Safe: Yes
The pthread_is_multithreaded_np() function returns true or false, indicating whether the current process has more than one thread. A return value of zero indicates that the calling thread is the only thread in the process. A value not equal to zero, indicates that there were multiple other threads in the process at the time of the call to pthread_is_multithreaded_np().
The total number of threads currently in the process can be determined by adding 1 to the return value of pthread_is_multithreaded_np().
Note: This function is not portable.
Authorities and Locks
None.
Parameters
None.
Return Value
- 0
- No other threads exist in the process.
- value
- There are currently value+1 total threads in the process.
Error Conditions
None.
Related Information
- The <pthread.h> header file. See Header files for Pthread functions.
- pthread_is_initialthread_np()--Check if Running in the Initial Thread
Example
Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.
#define _MULTI_THREADED #include <pthread.h> #include <stdio.h> #include "check.h" #define NUMTHREADS 3 void *threadfunc(void *parm) { int myHiId; int myId; pthread_t me = pthread_self(); printf("Inside the New Thread\n"); sleep(2); /* Sleep is not a very robust way to serialize threads */ return NULL; } int main(int argc, char **argv) { pthread_t thread[NUMTHREADS]; int rc=0; int theHiId=0; int theId=0; int i=0; printf("Enter Testcase - %s\n", argv[0]); printf("Create %d threads\n", NUMTHREADS); for (i=0; i<NUMTHREADS; ++i) { rc = pthread_create(&thread[i], NULL, threadfunc, NULL); checkResults("pthread_create()\n", rc); printf("Main: Currently %d threads\n", pthread_is_multithreaded_np() + 1); } printf("Join to threads\n"); for (i=0; i<NUMTHREADS; ++i) { rc = pthread_join(thread[i], NULL); checkResults("pthread_join()\n", rc); } if (rc = pthread_is_multithreaded_np()) { printf("Error: %d Threads still exist!\n", rc+1); exit(1); } printf("Main completed\n"); return 0; }
Output:
Enter Testcase - QP0WTEST/TPISMT0 Create 3 threads Main: Currently 2 threads Main: Currently 3 threads Main: Currently 4 threads Join to threads Inside the New Thread Inside the New Thread Inside the New Thread Main completed
API introduced: V4R3
[ Back to top | Pthread APIs | APIs by category ]