Prayer

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

pthread_key_t    key;
void echomsg(char *s)
{
    printf("thread auto free private varible %s\n",s);
    free(s);
    s = NULL;
}

void * child1(void *arg)
{
    //int tid = pthread_self();
    char * str = (char*)malloc(20);
    memset(str,0,20);
    sprintf(str,"%s","thread child1");
    printf("thread %s enter\n",str);
    pthread_setspecific(key,(void*)str);
    sleep(2);
    //printf("thread %d returns %d\n",tid,pthread_getspecific(key));
    sleep(5);
}

void * child2(void * arg)
{
    //int tid = pthread_self();
    char * str = (char*)malloc(20);
    memset(str,0,20);
    sprintf(str,"%s","thread child2");
    printf("thread %s enter \n",str);
    pthread_setspecific(key,(void*)str);
    sleep(1);
    //printf("thread %d returns %d\n",tid,pthread_getspecific(key));
    sleep(5);
}

int main(void)
{
    int tid1,tid2;
    printf("hello\n");
    pthread_key_create((pthread_key_t*)&key,(void*)echomsg);
    pthread_create((pthread_t*)&tid1,NULL,child1,NULL);
    pthread_create((pthread_t*)&tid2,NULL,child2,NULL);
    sleep(10);
    pthread_key_delete(key);
    return 0;
}