Shulou(Shulou.com)06/02 Report--

This article mainly introduces how to use XSI IPC shared memory allocation mutex to synchronize the threads between multiple processes in Camp Candle +. It has a certain reference value, and interested friends can refer to it. I hope you can learn a lot after reading this article. Let's take a look at it.

# include

# include

# include

# include

# include

# include

# include

# include

# include

# define handle_error_en (en, msg)\

Do {errno = en; perror (msg); exit (EXIT_FAILURE);} while (0)

Static pthread_mutex_t * mtx

Static void * original_owner_thread (void * ptr) {

Printf ("[original owner] Setting lock...\ n")

Pthread_mutex_lock (mtx)

Printf ("[original owner] Locked. Now exiting without unlocking.\ n")

Pthread_exit (NULL); / / exit after lock addition does not release lock

}

Int main () {

Pid_t pid_robust

Int shmid

/ / use XSI IPC to allocate mutex memory

Shmid = shmget (IPC_PRIVATE,sizeof (pthread_mutex_t), IPC_CREAT | IPC_EXCL)

/ / get memory area pointer

Mtx=shmat (shmid,0,0)

Pid_robust = fork ()

Int proc_status

Int ret

If (pid_robust 0) {

Pthread_t thr_p

Pthread_mutexattr_t attr

Pthread_mutexattr_init & attr)

Pthread_mutexattr_setpshared & attr,PTHREAD_PROCESS_SHARED)

Pthread_mutexattr_setrobust (& attr, PTHREAD_MUTEX_ROBUST)

Pthread_mutex_init (mtx, & attr)

Pthread_create (& thr_p, NULL, original_owner_thread, NULL)

} else if (0==pid_robust) {

Int err_code

Sleep (2)

Printf ("[fork main thread] Attempting to lock the robust mutex.\ n")

Err_code = pthread_mutex_lock (mtx)

If (err_code = = EOWNERDEAD) {

Printf ("[fork main thread] pthread_mutex_lock () returned EOWNERDEAD\ n")

Printf ("[fork main thread] Now make the mutex consistent\ n")

Err_code = pthread_mutex_consistent (mtx); / / call the function to change the owner of the lock, that is, the lock is changed from the previous owner to the host thread

If (err_code! = 0) {

Handle_error_en (err_code, "pthread_mutex_consistent")

}

Printf ("[fork main thread] Mutex is now consistent; unlocking\ n")

Err_code = pthread_mutex_unlock (mtx)

If (err_code = = 0) {

Printf ("[fork main thread] pthread_mutex_lock () unexpectedly succeeded\ n")

} else {

Handle_error_en (err_code, "pthread_mutex_unlock")

}

} else {

Printf ("[fork main thread] lock success!% d\ n", err_code)

}

Exit (0)

}

Printf ("parent main thread waiting fork process\ n")

Sleep (2)

If (waitpid (pid_robust,&proc_status,0) < 0) {

Printf ("[parent main thread] waiting for fork process error.\ n")

Return 127

}

If (WIFEXITED (proc_status)) {

Return 0

}

Return 127

}

Compile:

Gcc-lpthread-o muti_proc_thread_lock muti_proc_thread_lock.c

Results:

Thank you for reading this article carefully. I hope the article "how to synchronize threads between multiple processes using XSI IPC shared memory allocation mutex" shared by the editor is helpful to everyone. At the same time, I also hope that you will support and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.