소켓프로그래밍에서 쓰레드에 대해 궁금한점 올립니다

#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <string.h> 
#include <arpa/inet.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <pthread.h> 
 
#define BUFSIZE 100 
 
void * clnt_connection(void *arg); 
void send_message(char * message, int len); 
void error_handling(char *message); 
 
int clnt_number=0; 
int clnt_socks[10]; 
pthread_mutex_t mutx; 
 
int main(int argc, char **argv) 
{ 
  int serv_sock; 
 
  int clnt_sock; 
  struct sockaddr_in serv_addr; 
  struct sockaddr_in clnt_addr; 
  int clnt_addr_size; 
  pthread_t thread; 
 
  if(argc!=2) { 
    printf("Usage : %s <port>\n", argv[0]); 
    exit(1); 
  } 
 
  if(pthread_mutex_init(&mutx, NULL)) 
    error_handling("mutex init error"); 
 
  serv_sock=socket(PF_INET, SOCK_STREAM, 0); 
 
  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(atoi(argv[1])); 
 
  if(bind(serv_sock, (struct sockaddr*) &serv_addr, sizeof(serv_addr))==-1) 
    error_handling("bind() error"); 
 
  if(listen(serv_sock, 5)==-1) 
    error_handling("listen() error"); 
 
  while(1){ 
    clnt_addr_size=sizeof(clnt_addr); 
 
    clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_addr,&clnt_addr_size); 
 
    pthread_mutex_lock(&mutx); 
 
    <span>// accept함수는 클라이언트가 접속할때마다 accept를 하여 파일디스크립터를 계속 생성하는 건가요??</span>    clnt_socks[clnt_number++]=clnt_sock; 
    pthread_mutex_unlock(&mutx); 
 
    pthread_create(&thread, NULL, clnt_connection, (void*)clnt_sock);  
    printf("새로운 연결, 클라이언트 IP : %s \n", inet_ntoa(clnt_addr.sin_addr)); 
  } 
 
  return 0; 
} 
 
void * clnt_connection(void *arg) 
{ 
  int clnt_sock= (int)arg; 
  int str_len=0; 
  char message[BUFSIZE]; 
  int i; 
 
  while( (str_len=read(clnt_sock, message, sizeof(message))) != 0) 
    send_message(message, str_len); 
 
  pthread_mutex_lock(&mutx);
 
 <span>//여기 밑에부분 clnt_number는 여기 clnt_connection함수안에는 없는 변수입니다...전역변수로 선언된 clnt_number인 0이 들어가야되는게 아닌가요?? 그렇다면 결과가 이상하지 않나요?? </span>
  for(i=0; i<clnt_number; i++){  
 
    if(clnt_sock == clnt_socks[i]){ 
      for( ; i<clnt_number-1; i++) 
          clnt_socks[i]=clnt_socks[i+1]; 
      break; 
    } 
  } 
  clnt_number--; 
  pthread_mutex_unlock(&mutx); 
 
  close(clnt_sock); 
  return 0; 
} 
 
void send_message(char * message, int len) 
{ 
  int i; 
 
  pthread_mutex_lock(&mutx); 
  for(i=0; i<clnt_number; i++) 
    write(clnt_socks[i], message, len); 
  pthread_mutex_unlock(&mutx); 
} 
 
void error_handling(char *message) 
{ 
  fputs(message, stderr); 
  fputc('\n', stderr); 
  exit(1); 
}