多线程套接字编程服务器仅从 1 个客户端线程获取消息

Question

对于一个基准测试任务，我正在创建多个具有相同套接字描述符的服务器工作者和具有不同连接的客户端工作者。

尽管客户端线程正在为每个线程发送相同消息的副本。服务器显示它只收到每条消息的一个副本，而不是所有副本，由所有客户端线程发送。

对于 4 个线程和 2 条消息 {0,1} ，客户端输出

client 3Wrote 0
 client 1Wrote 1
 client 0Wrote 0
 client 1Wrote 0
 client 2Wrote 0
 client 3Wrote 1
 client 2Wrote 1

作为服务器输出的位置

Server 0 Received - 0
Server 2 Received - 1

为什么没有显示其余的消息？或者他们从未真正由客户发送？

void *clientWorker(void *threadarg) {
    struct workDetails *thisWork;
    thisWork = (struct workDetails *) threadarg;
    int threadcount = thisWork->threadcount;
    int chunkSize = thisWork->chunkSize;
    char *serverIp = thisWork->serverIp;
    char *dataStore = thisWork->dataStore;

    int sockfd;
    struct sockaddr_in serv_addr;
    struct hostent *server;
    char *buffer = (char *) calloc(chunkSize, sizeof(char));
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) error("ERROR opening client socket");
    server = gethostbyname(serverIp);
    if (server == NULL) error("Could not detect server by node name");

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *) server->h_addr,
          (char *) &serv_addr.sin_addr.s_addr,
          server->h_length);
    serv_addr.sin_port = htons(PORTNO);
    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
        error("Server is not up.");
    long totalPackets = oneGBtoByte / (chunkSize * threadcount);
    long i;
    for (i = 0; i < totalPackets; ++i) {
        sprintf(buffer, "%ld", i);
        if (write(sockfd, buffer, chunkSize) < 0)
            error("ERROR writing to socket");
        else {
            lock_guard<mutex> guard(cout_mutex);
            cout << " client " << thisWork->threadid << "Wrote " << i << endl;
        }
    }
    cout << " client " << thisWork->threadid << "Exit";
    pthread_exit((void *) NULL);
}

void *serverWorker(void *threadarg) {
    struct workDetails *thisWork;
    thisWork = (struct workDetails *) threadarg;
    int threadcount = thisWork->threadcount;
    int chunkSize = thisWork->chunkSize;
    char *dataStore = thisWork->dataStore;
    int sockfd = thisWork->sockfd;
    char *buffer = new char[chunkSize];

    while (1) {

        if(read(sockfd, buffer, chunkSize) > 0){
            lock_guard<mutex> guard(cout_mutex);
            cout << "Server " << thisWork->threadid << " Received - " << buffer << endl;
        }
    }
    pthread_exit((void *) NULL);
}

Answer 1

问题是accept connection code 在主线程中（在代码中不可见）。因此，尽管客户端尝试创建 4 个连接，但服务器只接受了一个连接。并且输出没有揭示这个问题，因为代码没有来回发送确认。 （没有乒乓球。理想情况下，大多数接收之后是发送确认，并且每次发送之后都是接收确认）。

当我将该接受连接代码移至线程工作者时。它按预期工作。

void *serverWorker(void *threadarg) {
    struct workDetails *thisWork;
    thisWork = (struct workDetails *) threadarg;
    int threadcount = thisWork->threadcount;
    int chunkSize = thisWork->chunkSize;
    char *dataStore = thisWork->dataStore;
    int sockfd = thisWork->sockfd;
    struct sockaddr_in cli_addr; // = thisWork->cli_addr;
    char *buffer = new char[chunkSize];


    listen(sockfd, 5);
    socklen_t clilen = sizeof(cli_addr);
    sockfd = ::accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
    if (sockfd < 0)
        error("ERROR on accept");

    while (1) {
        if (recv(sockfd, buffer, chunkSize, 0) > 0) {
            //lock_guard<mutex> guard(cout_mutex);
            //cout << "Server " << thisWork->threadid << " Received - " << buffer << endl;
            buffer[chunkSize] = NULL;
            strncat(dataStore, buffer, strlen(buffer));
            if (strlen(dataStore) == oneGBtoByte) {
                cout << "Done - " << endl;
                storeInfile(created, dataStore);
                break;
            }
        }
    }

    //End
    delete[] buffer;
    pthread_exit((void *) NULL);

}

@jeremy-friesner 或 @gil-hamilton 所说的都是真的。但是这些问题在这里并不重要，因为我只对收到的总字节感兴趣，而不是谁收到了哪个块。