accept函数为什么不阻塞

// sockSvr.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <WINSOCK2.H>
#pragma comment(lib,"ws2_32.lib")
//TCP服务器
void TCPServer()
{
    SOCKET hSockSvr = socket(AF_INET,SOCK_STREAM,0);
    SOCKADDR_IN addrSvr = {0};
    addrSvr.sin_family = AF_INET;
    addrSvr.sin_port = htons(5678);
    addrSvr.sin_addr.S_un.S_addr = INADDR_ANY;
    bind(hSockSvr,(SOCKADDR*)&addrSvr,sizeof(addrSvr));
    listen(hSockSvr,5);

    SOCKADDR_IN addClient = {0};
    int nLen = sizeof(addClient);
    SOCKET hSockClient = accept(hSockSvr,
        (SOCKADDR*)&addClient,&nLen);
    //数据收发
    char szRecv[100] = {0};
    recv(hSockClient,szRecv,100,0);
    printf("Client Data:%s\n",szRecv);
    //关闭套接字
    closesocket(hSockClient);
    closesocket(hSockSvr);
}
int main(int argc, char* argv[])
{
    //初始化socket库
    WSADATA ws = {0};
    WSAStartup(MAKEWORD(2,2),&ws);

    TCPServer();
   
    return 0;
}