Bốn kiến trúc phục vụ nhiều client

for (int i = 0; i < 2; ++i) {
    SOCKET c = accept(sv, NULL, NULL);
    printf("[%4lu ms] server: accept ket noi %d\n", tich()-t0, i+1);

    char dem[64];
    int n = recv(c, dem, 63, 0);       /* CHAN o day */
    if (n > 0) { dem[n] = 0; send(c, dem, n, 0); }

    printf("[%4lu ms] server: xong ket noi %d\n", tich()-t0, i+1);
    closesocket(c);
}

/* Hai client:
     CHAM  ket noi luc 100 ms, roi NGU 2 giay truoc khi gui
     NHANH ket noi luc 300 ms, gui ngay lap tuc            */

#include <sys/wait.h>
#include <signal.h>

/* Bo xu ly de thu hoac tien trinh con da chet.
   KHONG co dong nay thi moi client de lai mot tien trinh ZOMBIE. */
signal(SIGCHLD, SIG_IGN);

for (;;) {
    int c = accept(sv, NULL, NULL);
    if (c < 0) continue;

    pid_t con = fork();

    if (con == 0) {                 /* TIEN TRINH CON */
        close(sv);                  /* con khong can socket lang nghe */
        phuc_vu(c);
        close(c);
        _exit(0);                   /* _exit, KHONG phai exit */
    }

    close(c);                       /* CHA khong can socket ket noi */
    if (con < 0) { /* fork that bai */ }
}

static volatile LONG stt = 0;

static DWORD WINAPI phuc_vu(LPVOID a) {
    SOCKET c = *(SOCKET *)a;
    free(a);                            /* giai phong NGAY, xem ben duoi */

    LONG id = InterlockedIncrement(&stt);

    char dem[64];
    int n = recv(c, dem, 63, 0);
    if (n > 0) { dem[n] = 0; send(c, dem, n, 0); }

    printf("[%4lu ms] luong %ld: xong\n", tich()-t0, id);
    closesocket(c);
    return 0;
}

int main(void) {
    /* ... socket, bind, listen nhu cu ... */

    HANDLE h[2];
    for (int i = 0; i < 2; ++i) {
        SOCKET c = accept(sv, NULL, NULL);
        printf("[%4lu ms] server: accept ket noi %d, giao cho mot luong\n",
               tich()-t0, i+1);

        SOCKET *pc = malloc(sizeof *pc);    /* MOT ban sao cho MOI luong */
        *pc = c;
        h[i] = CreateThread(NULL, 0, phuc_vu, pc, 0, NULL);
    }
    WaitForMultipleObjects(2, h, TRUE, INFINITE);
}

#define SO_LUONG   16
#define HANG_CO   256

typedef struct {
    int             viec[HANG_CO];      /* mo ta tep cua ket noi */
    int             dau, duoi, co;
    pthread_mutex_t khoa;
    pthread_cond_t  co_viec;
    pthread_cond_t  co_cho;
    int             dung;
} Be;

static void be_them(Be *b, int fd) {
    pthread_mutex_lock(&b->khoa);
    while (b->co == HANG_CO && !b->dung)
        pthread_cond_wait(&b->co_cho, &b->khoa);    /* hang doi day */
    if (b->dung) { pthread_mutex_unlock(&b->khoa); close(fd); return; }

    b->viec[b->duoi] = fd;
    b->duoi = (b->duoi + 1) % HANG_CO;
    b->co++;
    pthread_cond_signal(&b->co_viec);
    pthread_mutex_unlock(&b->khoa);
}

static void *tho(void *a) {
    Be *b = (Be *)a;
    for (;;) {
        pthread_mutex_lock(&b->khoa);
        while (b->co == 0 && !b->dung)
            pthread_cond_wait(&b->co_viec, &b->khoa);
        if (b->co == 0 && b->dung) { pthread_mutex_unlock(&b->khoa); return NULL; }

        int fd = b->viec[b->dau];
        b->dau = (b->dau + 1) % HANG_CO;
        b->co--;
        pthread_cond_signal(&b->co_cho);
        pthread_mutex_unlock(&b->khoa);

        phuc_vu(fd);                    /* NGOAI vung khoa */
        close(fd);
    }
}