스레드 공부하는 초보자 인데요

#include<stdio.h>
#include<process.h>
#include<WinSock2.h>
#pragma comment(lib,"ws2_32.lib")
 
#define ACCEPT_CLIENT WM_USER+1
 
#define MY_PORT (short)4000
#define MAX_CLIENT 10
 
struct threadArgs{
	SOCKET *clientSocket;
	SOCKET listen;
	HANDLE messageHandler;
};
UINT WINAPI threadGetMessage(void* arg){
	BOOL bRet;
	MSG msg;
	memset(&msg, 0, sizeof(msg));
	WPARAM wParam;
	printf("start threadGetMessage\n");
	while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
	{ 
		printf("I get message\n");
		if (bRet == -1)
		{
			return -1;
		}
		else
		{
			TranslateMessage(&msg); 
			DispatchMessage(&msg); 
			if(msg.message == ACCEPT_CLIENT){
				printf("ACCEPT_CLIENT %d\n", (int)msg.wParam);
			}
		}
	}
 
	printf("stop threadGetMessage\n");
}
UINT WINAPI threadAccept(void* arg){
	printf("start threadAccept\n");
	threadArgs *client = (threadArgs*)arg;
	PostMessage((HWND)client->messageHandler, ACCEPT_CLIENT, (WPARAM)1234, NULL);
	int n = 0;
	while(1){
		for(int i = 0 ; i < MAX_CLIENT; i++) {
			SOCKET tempSock = accept(client->listen, NULL, NULL);
			if(tempSock == INVALID_SOCKET){
				printf("accept() error in thread");
				return -1;
			}
			if(client->clientSocket[i] == 0){
				client->clientSocket[i] = tempSock;
				PostMessage((HWND)client->messageHandler, ACCEPT_CLIENT, (WPARAM)i, NULL);
			}
		}
	}
	return 0;
}
int main(void){
	WORD wVersion = MAKEWORD(2,2);
	WSADATA wData;
	WSAStartup(wVersion, &wData);
	if(wData.wVersion != wVersion){
		printf("버전 불일치");
		return -1;
	}
 
	SOCKET listenSocket;
	listenSocket = socket(AF_INET
		, SOCK_STREAM
		, IPPROTO_TCP);
	if(listenSocket == INVALID_SOCKET){
		printf("listen Socket Error");
		return -1;
	}
 
	SOCKADDR_IN sockAddr;
	sockAddr.sin_family = AF_INET;
	sockAddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
	sockAddr.sin_port = MY_PORT;
	if(bind(listenSocket, (LPSOCKADDR)&sockAddr, sizeof(sockAddr)) == SOCKET_ERROR){
		printf("bind() 애러");
		closesocket(listenSocket);
		return -1;
	}
 
	if(listen(listenSocket, SOMAXCONN) == SOCKET_ERROR){
		printf("listen() 애러");
		closesocket(listenSocket);
	}
 
 
	HANDLE messageHandler = (HANDLE)_beginthreadex(
		NULL,
		0,
		threadGetMessage,
		(void*)NULL,
		0,
		NULL);
 
	threadArgs acceptArg;
	SOCKET clientSocket[MAX_CLIENT] = {0};
	acceptArg.clientSocket = clientSocket;
	acceptArg.listen = listenSocket;
	acceptArg.messageHandler = messageHandler;
 
	HANDLE acceptThread = (HANDLE)_beginthreadex(
		NULL,
		0,
		threadAccept,
		(void*)&acceptArg,
		0,
		NULL);
 
 
	WaitForSingleObject(acceptThread, INFINITE);
 
	WSACleanup();
	return 0;
}