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1998-12-13  Ulrich Drepper  <drepper@cygnus.com>

	* Examples/ex3.c: Wait until all threads are started before
	searching for the number to avoid race condition on very fast
	systems.
This commit is contained in:
Ulrich Drepper 1998-12-13 18:02:57 +00:00
parent 763babf874
commit e3743e2ffd
2 changed files with 19 additions and 3 deletions
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6
linuxthreads/ChangeLog
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@ -1,3 +1,9 @@
1998-12-13 Ulrich Drepper <drepper@cygnus.com>
* Examples/ex3.c: Wait until all threads are started before
searching for the number to avoid race condition on very fast
systems.
1998-12-08 Andreas Jaeger <aj@arthur.rhein-neckar.de> 1998-12-08 Andreas Jaeger <aj@arthur.rhein-neckar.de>
* sysdeps/pthread/pthread.h: Remove __pthread_setcanceltype * sysdeps/pthread/pthread.h: Remove __pthread_setcanceltype

16
linuxthreads/Examples/ex3.c
View File

@ -19,6 +19,7 @@ void print_it(void *);
pthread_t threads[NUM_THREADS]; pthread_t threads[NUM_THREADS];
pthread_mutex_t lock; pthread_mutex_t lock;
int tries; int tries;
volatile int started;
int main(int argc, char ** argv) int main(int argc, char ** argv)
{ {
@ -33,8 +34,8 @@ int main(int argc, char ** argv)
pthread_mutex_init(&lock, NULL); pthread_mutex_init(&lock, NULL);
/* Create the searching threads */ /* Create the searching threads */
for (i=0; i<NUM_THREADS; i++) for (started=0; started<NUM_THREADS; started++)
pthread_create(&threads[i], NULL, search, (void *)pid); pthread_create(&threads[started], NULL, search, (void *)pid);
/* Wait for (join) all the searching threads */ /* Wait for (join) all the searching threads */
for (i=0; i<NUM_THREADS; i++) for (i=0; i<NUM_THREADS; i++)
@ -74,7 +75,13 @@ void *search(void *arg)
/* use the thread ID to set the seed for the random number generator */ /* use the thread ID to set the seed for the random number generator */
/* Since srand and rand are not thread-safe, serialize with lock */ /* Since srand and rand are not thread-safe, serialize with lock */
pthread_mutex_lock(&lock);
/* Try to lock the mutex lock --
if locked, check to see if the thread has been cancelled
if not locked then continue */
while (pthread_mutex_trylock(&lock) == EBUSY)
pthread_testcancel();
srand((int)tid); srand((int)tid);
i = rand() & 0xFFFFFF; i = rand() & 0xFFFFFF;
pthread_mutex_unlock(&lock); pthread_mutex_unlock(&lock);
@ -87,6 +94,9 @@ void *search(void *arg)
pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL); pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL); pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
while (started < NUM_THREADS)
sched_yield ();
/* Push the cleanup routine (print_it) onto the thread /* Push the cleanup routine (print_it) onto the thread
cleanup stack. This routine will be called when the cleanup stack. This routine will be called when the
thread is cancelled. Also note that the pthread_cleanup_push thread is cancelled. Also note that the pthread_cleanup_push