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#define _GNU_SOURCE /* For pthread_getattr_np */
#include <pthread.h>
#include <unistd.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
static pthread_once_t printed_p = PTHREAD_ONCE_INIT;
void print_it ()
{
int rc;
pthread_attr_t foo;
size_t size;
rc = pthread_getattr_np (pthread_self(), & foo);
assert (rc == 0);
rc = pthread_attr_getstacksize(&foo, &size);
assert (rc == 0);
printf ("stacksize=%u\n", size);
rc = pthread_attr_destroy (&foo);
assert (rc == 0);
}
void *tfunc(void *arg)
{
/* Choose some random thread to print stack size */
(void) pthread_once(&printed_p, &print_it);
return NULL;
}
#define MAXTHREADS 4096
int
main(int argc, char **argv)
{
pthread_t thr[MAXTHREADS];
pthread_attr_t attr;
int numthreads;
int stacksize;
int rc;
int threads_created = 0;
size_t i;
if (argc != 3) {
fprintf(stderr, "Usage: %s numthreads stacksize|0\n", argv[0]);
return -1;
}
numthreads = atoi(argv[1]);
if (numthreads > MAXTHREADS) {
numthreads = MAXTHREADS;
}
stacksize = atoi(argv[2]);
rc = pthread_attr_init(&attr);
assert (rc == 0);
if (stacksize > 0) {
rc = pthread_attr_setstacksize(&attr, (size_t) stacksize);
assert (rc == 0);
}
for (i = 0; i < numthreads; i++) {
rc = pthread_create(&thr[i], (stacksize == 0 ? NULL : &attr), tfunc, NULL);
/* On systems with not enough memory, pthread_create() can fail
* after creating lots of threads. Just ignore this error (if
* we've already created at least 100 threads). */
if (rc == EAGAIN && threads_created > 100)
break;
assert (rc == 0);
threads_created++;
}
/* Wait for all the threads to finish (otherwise we can exit
* before one of our threads has the chance to print the stack
* size). */
for (i = 0; i < threads_created; i++) {
pthread_join(thr[i], NULL);
}
rc = pthread_attr_destroy(&attr);
assert (rc == 0);
return 0;
}
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