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Function of retval in pthread_join


By : Steven Porter
Date : July 31 2020, 03:00 PM
it should still fix some issue I'm learning threading in C in OS. I don't know why following code is giving me segmentation fault. Can anyone help me here? I am also confused a bit about how pthread_join uses its argument void ** retval. What is its function? , This is not correct:
code :
int* arg = *((int*)vargp);  
int* arg = (int*) vargp;


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pthread_join function in c


By : user3325649
Date : March 29 2020, 07:55 AM
will help you Yes that is what pthread_join is meant to do. It has the calling thread wait until the created thread has done its work. If you don't have it, your main thread terminates the whole process before your fn thread had a chance to print.
If for one reason you want to terminate the main thread and keep all other threads of the process running, you'd have to terminate it with pthread_exit, not with a return statement nor with a call to exit.

Why is the return value of pthread_join() not changing with each call to pthread_join()


By : Dennis Betten
Date : March 29 2020, 07:55 AM
may help you . This program works fine if the user enters only 1 number on the command line. It will factor out the prime factors and output them to the console just fine.
code :
pthread_create(&t_id[i], NULL, primeFactors, *(argv+1))

pthread_join void **retval


By : Sergey
Date : March 29 2020, 07:55 AM
like below fixes the issue If you understand that pthread_join() will pick the return value of the thread callback then you should return from it like this
code :
#include <stdio.h>
#include <stdint.h>
#include <pthread.h>

void *
threadHandler(void *data)
{
    printf("arg: %s\n", (char *) data);
    return (void *) 0;
}

int 
main(void)
{
    pthread_t thread;
    const char *string;
    void *number;

    string = "N";
    if (pthread_create(&thread, NULL, threadHandler, (void *) string) != 0)
        return -1;
    pthread_join(thread, &number);
    printf("%d\n", ((int) (intptr_t) number));
    return 0;
}

return retval() if retval() -- is there a way to write that in Ruby without the retval function being called twice?


By : reini
Date : March 29 2020, 07:55 AM
To fix the issue you can do Suppose I have this code , Here's another variation of the same thing

glibc pthread_join crash when call pthread_join() twice


By : Bala Murali
Date : March 29 2020, 07:55 AM
wish help you to fix your issue pthread_join calls pthread_detach after the thread has terminated. pthread_detach releases all the threads resources when the thread terminates.
From the documentation of pthread_detach
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