fprintf() и треды

#include <windows.h>
#include <stdio.h>

FILE *fp;

DWORD WINAPI
test (void*)
{
    fprintf(fp, "test to file in thread\n");
    fprintf(stdout, "test to stdout in thread\n");

    return 0;
}

int main ()
{
    HANDLE lpHandle;
    DWORD ThreadId;
   
    fp = fopen("test.txt", "a");

    fprintf(fp, "test to file\n");
    fprintf(stdout, "test to stdout\n");

    lpHandle = CreateThread(NULL,0,test,NULL,0,&ThreadId);

    WaitForSingleObject(lpHandle, INFINITE);
    fclose(fp);

    return 0;
}