通信过程结束后退出线程

Question

我正在使用Pthread在C中使用多线程服务器应用程序。如果客户端发送关闭连接的请求，我可以退出线程并释放它使用的资源。我正在粘贴下面的代码

MAIN.C

#include "extern.h" 

int thread_counter = 0;
int rc;

void main(int argc, char** argv){

    int sock_desc = 0, connfd = 0;
    struct sockaddr_in serv_addr;
    int clntSock; 
    struct sockaddr_in echoClntAddr; 
    int n = 0;   

   pthread_t thr;

    sock_desc = socket(AF_INET, SOCK_STREAM, 0); 

    if(sock_desc < 0 )
       dieWithError("Unable to open Socket\n");

    fcntl(sock_desc, F_SETFL, fcntl(sock_desc, F_GETFL, 0) | O_NONBLOCK); 

    memset(&serv_addr,0,sizeof(serv_addr)); 

    serv_addr.sin_family = AF_INET ;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(7024);

    if(bind(sock_desc, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) 
       dieWithError("bind failed\n");


    if(listen(sock_desc,MAX_CONNECTIONS) < 0)
       dieWithError("listen failed\n");  

       clntSock = sizeof(struct sockaddr);
       int i =0;

    while(1){

         connfd = accept(sock_desc, (struct sockaddr *)&echoClntAddr,(socklen_t*)&clntSock);


         if(connfd > 0){  
            puts("Connection accepted");

            if(pthread_create( &thr, NULL ,  connection_handler , (void*)connfd) < 0){
               perror("could not create thread");
            }

            puts("Handler assigned");

        }    
    }

}

    void dieWithError(char *errormsg){ 
         printf("%s", errormsg);    
    }

HandleConnection.C

#include "extern.h"

void *connection_handler(void *socket_desc){
    int sock = (int) socket_desc;
    int read_size;  
    char client_message[2000];
    int i;
    int rc = 5;



    while(1){
        read_size = recv(sock , client_message , 2000 , 0); 
        if(read_size > 0){

       client_message[read_size] = '\0';
        printf("%s",client_message); 

        }

        memset(client_message, 0, 2000);


    if(read_size == 0){
       puts("Client disconnected");
     pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
    pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS,NULL);
       fflush(stdout);
      rc = close(sock);

       break;
    }
    else if(read_size == -1){
            perror("received failed");
            break;
    }

} 

}

如何以及在何处编写例程以在其工作结束后退出线程。我尝试使用pthreads_cancel，但它没有帮助，理由可能是我没有正确使用它。