socket网络编程，两个客户端线程同时跟服务器端进行网络通信时遇到有关问题

socket网络编程，两个客户端线程同时跟服务器端进行网络通信时遇到问题
主线程（线程1）是一个与服务器端对话的普通线程
线程2的作用是接收报警消息，服务器端安装了报警采集装置，当有报警发生时会向线程2发送一条报警消息。
因为大部分时间都没有报警发生，服务器端没有给线程2发送任何消息，所以线程2应该是阻塞在recv函数那儿的。但是我运行程序的时候线程2中的recv（）函数并没有阻塞,当报警发生时，线程2也收不到报警了
我怀疑是线程1的socket通信对线程2产生了影响，但是我把_beginthread(client , 0, NULL); //线程2启动 放到main（）函数中的最后（while循环前面）时还是这个结果。  

请高人指点！不慎感激！

运行结果是：
Sock 1 ============== 1924
Sock 2 ============== 1920
Thread 2 is Waitting.....................
Thread 1 Hello,Jim! I'm Lilei
Thread 1 Hello Lilei,I'm Jim
Thread 1 I wang you come to my home tonight
Thread 1 Sorry,I have no time tonight
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
Thread 2 len ===== 0
.
.
.
.
.

代码如下：
include <stdio.h>
#include <WINSOCK2.H>
#include <process.h>
#pragma comment(lib, "Ws2_32.lib")

void client(void *);

int main()
{

_beginthread(client , 0, NULL); //线程2启动
int sock;
WORD wVersionRequested;
WSADATA wsaData;
int err;

wVersionRequested = MAKEWORD( 2, 2 );

err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) 
{
printf("Can't find a usable WinSock DLL\n");
return -1;
}

sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock < 0)
{
printf("Create socket error: %d\n", WSAGetLastError());
return -1;
}
printf("Sock 1 ============== %d\n",sock);

sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_port = htons(6000);
addr.sin_addr.s_addr = inet_addr("112.95.146.7");

int ret;

ret = connect(sock, (sockaddr*)&addr, sizeof(sockaddr_in));
if (ret < 0)
{
printf("Connect error :%d\n", WSAGetLastError());
return -1;
}

char recvbuf[1024] = {0};
char sendbuf[1024] = {0};
int len;

  strcpy(sendbuf, "Hello,Jim! I'm Lilei");
  len = send(sock, sendbuf, strlen(sendbuf), 0);
  printf("Thread 1 %s\n", sendbuf);
  memset(sendbuf, 0, sizeof(sendbuf));
  
len = recv(sock, recvbuf, sizeof(recvbuf), 0); //server回复"Hello Lilei,I'm Jim"
printf("Thread 1 %s\n", recvbuf);
memset(recvbuf, 0, sizeof(recvbuf));

Sleep(1000);

strcpy(sendbuf, "I wang you come to my home tonight");
len = send(sock, sendbuf, strlen(sendbuf), 0);
printf("Thread 1 %s\n", sendbuf);
memset(sendbuf, 0, sizeof(sendbuf));

len = recv(sock, recvbuf, sizeof(recvbuf), 0); //server回复"Sorry,I have no time tonight"
printf("Thread 1 %s\n", recvbuf);
memset(recvbuf, 0, sizeof(recvbuf));
while(1)
{

};
}


void client(void *)
{
int sock2;
WORD wVersionRequested;
WSADATA wsaData;
int err;

wVersionRequested = MAKEWORD( 2, 2 );

err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) 
{
printf("Can't find a usable WinSock DLL\n");
return ;
} 

sock2 = socket(AF_INET, SOCK_STREAM, 0);
if (sock2 < 0)
{
printf("Create socket error: %d\n", WSAGetLastError());
return ;
}
printf("Sock 2 ============== %d\n",sock2);

sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_port = htons(63456);
addr.sin_addr.s_addr = inet_addr("112.95.146.7");

int ret,len;
char recvbuf[1024] = {0};

ret = connect(sock2, (sockaddr*)&addr, sizeof(sockaddr_in));