pthread_join function

C

Function

Reference manual

@see pthread_create function

The pthread_join function is used to wait for a thread to terminate and retrieve its exit status. It blocks the calling thread until the specified thread terminates.

Syntax

#include <pthread.h>

int pthread_join(pthread_t thread, void **retval);

Parameters

• thread: The thread ID of the thread to be joined. This thread must be joinable.

• retval: A pointer to a variable where the exit status of the joined thread will be stored. This value can be NULL if the exit status is not required.

Return value

• If the thread is successfully joined, the function returns 0.

• If an error occurs, a non-zero error code is returned. Possible error codes include EINVAL (invalid thread ID or already joined thread) and ESRCH (no thread could be found with the specified ID).

Usage example

In this example, the program creates a new thread using pthread_create and waits for it to terminate using pthread_join. The exit status of the joined thread is stored in the thread_return_value variable.

#include <stdio.h>
#include <pthread.h>

void *thread_function(void *arg)
{
    // Thread logic
    return (NULL);
}

int main()
{
    pthread_t thread;
    void *thread_return_value;
    int join_result;

    pthread_create(&thread, NULL, thread_function, NULL);
    join_result = pthread_join(thread, &thread_return_value);
    if (join_result == 0)
        printf("Thread joined successfully\n");
    else
        fprintf(stderr, "Error joining thread: %d\n", join_result);
    // Main thread continues execution after the joined thread has terminated
    return (0);
}