Conditional variable pthread_cond_t in a thread

#include <pthread.h> #include <stdio.h> #include <stdlib.h>pthread_mutex_t mutex = pthread_mutex_ initializer;/* Initialize the mutex */pthread_cond_t cond = pthread_cond_initializer;/* Initialize the condition variable */void *thread1 (void *); void *thread2 (    void *); int i=1;int main (void) {pthread_t t_a;    pthread_t T_b; Pthread_create (&t_a,null,thread1, (void *) null);/* Create Process t_a*/pthread_create (&t_b,null,thread2, (void *) NULL) ; /* Create process t_b*/pthread_join (t_a, NULL);/* Wait for process t_a to end */pthread_join (t_b, NULL);/* Wait for process t_b end */Pthread_mutex_destroy (&am    P;mutex);    Pthread_cond_destroy (&cond); Exit (0);}        void *thread1 (void *junk) {for (i=1;i<=6;i++) {printf ("\n1111111111 I was%d 111111111111\n", i);        Pthread_mutex_lock (&mutex);/* Lock Mutex */printf ("Thread1:lock%d\n", __line__);            if (i%3==0) {printf ("Thread1:signal 1 line:%d i is%d \ n", __line__,i);   Pthread_cond_signal (&cond);/* condition change, send signal, notify T_b process */printf ("Thread1:signal 2%d\n", __line__); sleep (1);}     Pthread_mutex_unlock (&mutex);/* Unlock Mutex */printf ("Thread1:unlock%d\n\n", __line__); sleep (1);}}        void *thread2 (void *junk) {while (i<6) {printf ("2222222222222 in Pthread2 I was%d 222222222222222222 \ n", i);  Pthread_mutex_lock (&mutex);p rintf ("Thread2:lock line:%d i is%d\n", __line__,i), if (i%3!=0) {printf ("thread2:wait            1%d\n ", __line__); Pthread_cond_wait (&cond,&mutex);/* Unlocks the mutex and waits for cond to change */printf ("Thread2:wait 2%d\n", __line__);p rintf ("        Thread2:i is%d\n\n ", i);} Pthread_mutex_unlock (&mutex);p rintf ("Thread2:unlock%d\n\n", __line__); sleep (1);}}

Compile:

GCC Test.c-o test-lpthread

Logic:

The main function creates two threads

Thread 1: Accumulate I, each time mutually exclusive lock when I is a multiple of 3 to send change the condition signal to thread 2;

Thread 2: When I <6, the mutual exclusion lock operation, when not a multiple of 3 to wait for the adjustment to change the signal, blocking the thread;

When 1=1;

Thread 2:i not divisible by 3 blocking wait condition change signal;
Thread 1: normal cumulative i=2

i=2
Thread 2: Blocking
Thread 1: Not divisible by 3, normal cumulative

I=3
Thread 2: Blocking
Thread 1: Divide evenly, accept to send the condition change signal;
Thread 2 unlocked, normal operation sleep a second

I=4
Thread 2:i equals four blocking
Thread 1: Not divisible by 3, normal cumulative

I=5
Thread 2:i equals four blocking
Thread 1: Not divisible by 3, normal cumulative

I=6
Thread 2: Receive a signal to unlock
Thread 1: Sending a signal

Run:

2222222222222 in Pthread2 I was 1 222222222222222222
Thread2:lock line:46 i is 1
Thread2:wait 1 48

1111111111 i is 1 111111111111
Thread1:lock 27
Thread1:unlock 35

1111111111 I is 2 111111111111
Thread1:lock 27
Thread1:unlock 35

1111111111 i is 3 111111111111
Thread1:lock 27
Thread1:signal 1 line:29 i is 3
Thread1:signal 2 31
Thread1:unlock 35

Thread2:wait 2 53
THREAD2:I is 3

Thread2:unlock 57

2222222222222 in Pthread2 I was 3 222222222222222222
Thread2:lock line:46 i is 3
Thread2:unlock 57

1111111111 I is 4 111111111111
Thread1:lock 27
Thread1:unlock 35

2222222222222 in Pthread2 I was 4 222222222222222222
Thread2:lock line:46 I is 4
Thread2:wait 1 48

1111111111 i is 5 111111111111
Thread1:lock 27
Thread1:unlock 35

1111111111 I is 6 111111111111
Thread1:lock 27
Thread1:signal 1 line:29 i is 6
Thread1:signal 2 31
Thread1:unlock 35

Thread2:wait 2 53
THREAD2:I is 6

Thread2:unlock 57

Reference Link: http://blog.csdn.net/zclongembedded/article/details/7337729

Conditional variable pthread_cond_t in a thread