使用Socket接收UDP数据包时服务器端卡顿问题求助

我在服务器端接收客户端发送的6000个UDP数据包时，出现以下异常：

• 低熵数据包（全零内容）：接收约4000-5000个包后卡顿，需等待30-40秒才能继续接收剩余数据包
• 高熵数据包（随机内容）：仅能接收约80个包，之后直接卡住，无法接收后续数据包

我原本猜测是接收缓冲区被填满且未及时清理，但调整缓冲区大小后，服务器处理效率并未提升。

server.c #

char buffer[payload_size];

int nBuf = 32*1024;
int s = setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, (const char*)&nBuf, sizeof(int));
if (s < 0) {
    perror("SO_RCVBUF");
    free(cf);
    exit(EXIT_FAILURE);
}

printf("receiving low entropy packets\n");
for (int i = 0; i < packet_num; i++) {
    //memset(&buffer, 0, payload_size);
    bzero(buffer, payload_size);
    int n = (int) recvfrom(sockfd, buffer, payload_size, MSG_WAITALL, 
        (struct sockaddr *)&client_addr, &cli_addr_len);
    printf("i: %d\n", i);
    if (i == 0 && n > 0) {
        low_start = clock();
    }
}
memset(buffer, 0, payload_size);
low_end = clock();

sleep(1);
printf("receiving high entropy packets\n");
for (int i = 0; i < packet_num; i++) {
    memset(&buffer, 0, payload_size);
    int n = (int) recvfrom(sockfd, buffer, payload_size, MSG_WAITALL,
         (struct sockaddr *)&client_addr, &cli_addr_len);
    printf("i: %d\n", i);
    if (i == 0 && n > 0) {
        high_start = clock();
    }
}
high_end = clock();

client.c #

char buffer[payload_size];
memset(&buffer, 0, payload_size);

int nBuf = 32*1024;
setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, (const char*)&nBuf, sizeof(int));


for (int i = 0; i < num_packets; i++) {
    buffer[0] = (char) ((i >> 8) & 0xFF);
    buffer[1] = (char) (i & 0xFF);
    printf("i: %d\n", i);
    if (sendto(sockfd, buffer, payload_size, 0, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("failed to send udp packet, low entropy");
        free(cf);
        close(sockfd);
        exit(1);
    }
}
printf("low entropy packets sent\n");
sleep(interval_time);

char random[payload_size];
get_random_byte(payload_size, random);
for (int i = 0; i < num_packets; i++) {
    random[0] = (char) ((i >> 8) & 0xFF);
    random[1] = (char) (i & 0xFF);
    printf("i: %d\n", i);
    if (sendto(sockfd, random, payload_size, 0, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("failed to send udp packet, high entropy");
        free(cf);
        close(sockfd);
        exit(1);
    }
}
printf("high entropy packets sent\n");

内容的提问来源于stack exchange，提问作者Chris C