pthread_cancel() in C with example

prerequisite: Multithreading, pthread_self() in C with Example

pthread_cancel() = This function cancel a particular thread using thread id. This function send a cancellation request to the thread.

Syntax : – int pthread_cancel(pthread_t thread);

First Program : – Cancel self thread

 

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// C program to demonstrates cancellation of self thread 
// using thread id
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
  
void* calls(void* ptr)
{
    printf("GeeksForGeeks");
  
    // To exit the current thread
    // pthread_self() return the particular thread id
    pthread_cancel(pthread_self()); 
      
    return NULL;
}
  
int main()
{
    // NULL when no attribute
    pthread_t thread;
  
    // calls is a function name
    pthread_create(&thread, NULL, calls, NULL); 
  
    // Waiting for when thread is completed
    pthread_join(thread, NULL); 
  
    return 0;
}

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Output:


GeeksForGeeks



 


If you use Linux then compile this program  gcc program_name.c -lpthread 


Second Program : –  Cancel other thread


 











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// C program to demonstrates cancellation of another thread  


// using thread id 


#include <stdio.h> 


#include <unistd.h> 


#include <sys/types.h> 


#include <pthread.h> 


  


// To Count 


int counter = 0;  


  


// for temporary thread which will be  


// store thread id of second thread 


pthread_t tmp_thread;  


  


// thread_one call func 


void* func(void* p)  


{ 


    while (1) { 


  


        printf("thread number one\n"); 


        sleep(1);   // sleep 1 second 


        counter++;    


        


        // for exiting if counter = = 5 


        if (counter = = 2) { 


  


            // for cancel thread_two 


            pthread_cancel(tmp_thread);  


  


            // for exit from thread_one  


            pthread_exit(NULL);   


        } 


    } 


} 


  


// thread_two call func2 


void* func2(void* p)  


{ 


  


    // store thread_two id to tmp_thread 


    tmp_thread = pthread_self();  


  


    while (1) { 


        printf("thread Number two"); 


        sleep(1); // sleep 1 second 


    } 


} 


  


// Driver code 


int main() 


{ 


  


    // declare two thread 


    pthread_t thread_one, thread_two;  


  


    // create thread_one 


    pthread_create(&thread;_one, NULL, func, NULL); 


  


    // create thread_two  


    pthread_create(&thread;_two, NULL, func2, NULL);  


  


    // waiting for when thread_one is completed 


    pthread_join(thread_one, NULL);  


  


    // waiting for when thread_two is completed 


    pthread_join(thread_two, NULL);  


  


}



















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Output:


thread number one
thread number two
thread number one 
thread number two



 


If you use Linux then compile this program gcc program_name.c -lpthread


This article is contributed by Devanshu Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.


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