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Thread termination:

1.start_routine callback function executes return

two。 The thread itself calls pthread_exit ()

3. Other threads call pthread_cancel (ID) to terminate this process

Any thread calls exit () to cause the entire process to exit.

Thread recycling: the thread defaults to joinable state, which needs to be recycled using pthread_join after termination; the child thread is in unjoinable state after being separated from the main thread using pthread_detach, and the system and other threads automatically reclaim resources after exiting.

Common function calls are as follows:

Pthread_exit (): ends this thread

# include

Void pthread_exit (void * retval)

Parameter meaning:

Retval: the thread returns the value, and other threads call pthread_join () to receive it.

Pthread_cancel (): sends a cancellation request to the specified thread and reclaims it using pthread_join

# include

Int pthread_cancel (pthread_t thread)

Parameter meaning:

Return value: a successful execution returns 0, and a successful execution does not necessarily terminate the specified thread. A failed execution returns an error number.

Pthread_join (): wait for the thread to stop reclaiming resources and get the return value retval

# include

Int pthread_join (pthread_t thread, void * * retval)

Parameter meaning:

Thread: thread ID.

Retval: stores the return value of the recycling thread.

Return value: 0 for success and error number for failure.

Pthread_detach (): detach the thread. After the thread terminates, the system cleans up automatically. After separation, you can no longer use join to get the state.

# include

Int pthread_detach (pthread_t thread)

Return value: 0 for success and error number for failure.

The code of this chapter is in the thread/ directory, experiment 1: path is: 11_Linux system Development Advanced\ Linux system programming _ chapter usage materials.

Use pthread_cancel to let the thread exit, pthread_join to recycle, the code in cancel.c:

Compile: gcc cancel.c-o cancel-lpthread, run the result:

Use pthread_exit to let the thread exit, pthread_join reclaims the thread resources, and the code is in the / thread/exit/ directory

The thread exits using pthread_exit in turn, and then pthread_join reclaims the thread in turn, main.c:

When the compilation runs, you can see that the thread exits sequentially and prints the return value of pthread_exit:

Experiment 3:

Use pthread_detach () to set thread separation, after pthread_exit () exits, the system automatically reclaims, and finally calls pthread_join () to find an error, indicating that the thread is automatically released after thread separation.

The experimental code is available in the detach.c: path: 11_Linux system Development Advanced\ Linux system programming _ chapter.

Compile, gcc-o detach detach.c-lpthread. The result is as follows. It is found that an error is reported using pthread_join ():

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