Pthread_mutex_lock thread Lock Use simple example

#define __use_largefile64
#define _largefile64_source
#ifndef _gnu_source
#define _gnu_source
#endif
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
#include <pthread.h>
#include ". /errors.h "
#define Mutex_lock


pthread_mutex_t Mutex;
void *thread_function_even (void *inpara)
{
int *num = (int *) Inpara;
Long unsigned int thread_num = Pthread_self ();
Pthread_detach (Thread_num); /*detach to is an independent thread*/
while (1)
{
#ifdef Mutex_lock
Pthread_mutex_lock (&mutex);
#endif
*num = (*num * 2)% 100;
Usleep (1);
printf ("int thread_function_even,num:%d,is even:%d\n", *num, (0 = = *num% 2));
#ifdef Mutex_lock
Pthread_mutex_unlock (&mutex);
#endif
}
}
void *thread_function_odd (void *inpara)
{
int *num = (int *) Inpara;
Long unsigned int thread_num = Pthread_self ();
Pthread_detach (Thread_num); /*detach to is an independent thread*/
while (1)
{
#ifdef Mutex_lock
Pthread_mutex_lock (&mutex);
#endif
*num = (*num * 2)% 100 + 1;
Usleep (1);
printf ("int thread_function_odd,num:%d,is even:%d\n", *num, (0 = = *num% 2));
#ifdef Mutex_lock
Pthread_mutex_unlock (&mutex);
#endif
}
}
int main (int argc, char *argv[])
{
/*mutex is a lock,everyone only can operate an array by get the mutex*/
#ifdef Mutex_lock
Pthread_mutex_init (&mutex, NULL);
#endif


/*create the threads,one change the NUM to even,the and the NUM to odd*/
int i = 0;
pthread_t thread_even,thread_odd;
Pthread_create (&thread_even, NULL, Thread_function_even, &i);
Pthread_create (&thread_odd, NULL, thread_function_odd, &i);


while (1);
#ifdef Mutex_lock
Pthread_mutex_destroy (&mutex);
#endif

}

1. Compilation: GCC main.c-lpthread-g

2. Run:./a > 10 seconds after ctrl C stops

3. Verify that the lock is valid, the following two commands do not search the result:

Cat 1|grep Thread_function_odd|grep "Even:1"
Cat 1|grep Thread_function_even|grep "even:0"

4. Remove the lock in the code: note # define Mutex_lock

5. After removing the verification is not locked after the correct, the two command in step 3 can search the results

Cat 1|grep Thread_function_odd|grep "Even:1"
Cat 1|grep Thread_function_even|grep "even:0"

6. The principle of the code: Create two threads, two threads all operate the same integer, an integer only to an even number, an integer only to the odd, lock the case, the even-numbered threads print all the numbers are even, odd-numbered threads are all odd numbers printed

Pthread_mutex_lock thread Lock Use simple example