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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

 



// 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;
}

Output:

GeeksForGeeks

 

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

Second Program : – Cancel other thread

 

// 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 ");
        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); 
  
}

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

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



This article is attributed to GeeksforGeeks.org

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