ZeroMQ REQ/REP性能

Question

考虑以下两个过程：

sender.cpp：

#include <zhelpers.h> 
... 
zmq::context_t ctx(1); 
... 
void foo(int i) 
{ 
    zmq::socket_t sender(ctx, ZMQ_REQ); 
    sender.connect("tcp://hostname:5000"); 

    std::stringstream ss; 
    ss <<"bar_" <<i; 
    std::string bar_i(std::move(ss.str()); 

    s_sendmore(sender, "foo "); 
    (i != N) ? s_send(sender, bar, 0) : s_send(sender, "done", 0); 
    s_recv(sender); 
} 

int main() 
{ 
    for(int i=0; i<=100000; ++i) 
     foo(i); 
    return 0; 
} 

receiver.cpp

#include <zhelpers.h> 
... 
int main() 
{ 
    zmq::context_t ctx(1); 
    zmq::socket_t rcv(ctx, ZMQ_REP); 
    rcv.bind("tcp://*:5000"); 

    std::string s1(""); 
    std::string s2(""); 

    while(s2 != "done") 
    { 
     s1 = std::move(s_recv(rcv)); 
     s2 = std::move(s_recv(rcv)); 
     std::cout <<"received: " <<s1 <<" " <<s2 <<"\n"; 
     s_send(rcv, "ACK"); 
    } 

    return 0; 
} 

让我们先从两个过程。我会想到的是，接收器进程将接收方发送给它的所有信息，它会打印出：

foo bar_1 
foo bar_2 
... 

等等，直到：

... 
foo bar_100000 

我预计它会做到这一点没有任何阻碍。

我的问题是，接收器总是围绕28215th迭代（总是围绕该数字!!!）并且阻塞直到一分钟左右。然后进一步到100000，但有时它会再次粘住。我的问题当然是：为什么会发生这种情况？我该如何解决它？

我试图把'发送者'放在全局范围内的foo（。）中，然后它就起作用了：在这种情况下，所有打印输出从1到100000顺利且超快速地进行，没有任何阻塞当然在这种情况下，每次调用foo（。）时都不会创建套接字）。但不幸的是，在我的代码中，我无法做到这一点。

我想了解为什么会出现此块。

Answer 1

首先，你的例子不是非常可行的，因为它们不编译。因此，这里有一些exapmles，应该是接近你的意图和实际编译

sender.cpp

#include <zmq.hpp> 
#include <string> 
#include <iostream> 
#include <string> 

void send(const std::string& msg) 
{ 
    // Prepare our context and socket 
    zmq::context_t context (1); 
    zmq::socket_t socket (context, ZMQ_REQ); 

    std::cout << "Connecting to receiver ..." << std::endl; 
    socket.connect ("tcp://localhost:5555"); 

    zmq::message_t request (100); 
    memcpy (request.data(), msg.c_str(), 100); 
    std::cout << "Sending message " << msg << "..." << std::endl; 
    socket.send (request); 
} 

int main() 
{ 
    for(int i = 0; i < 100000; ++i) 
    { 
     send(std::to_string(i)); 
    } 
    send("done"); 
} 

使用一些临客

g++ -std=c++11 -I/home/dev/cppzmq -I/home/dev/libzmq/include sender.cpp -lzmq -o sender 

receiver.cpp

#include <zmq.hpp> 
#include <string> 
#include <cstring> 
#include <iostream> 

int main() { 
    // Prepare our context and socket 
    zmq::context_t context (1); 
    zmq::socket_t socket (context, ZMQ_REP); 
    socket.bind ("tcp://*:5555"); 

    char buf[100] = {0}; 
    while (std::string(buf).compare("done")) { 
     zmq::message_t request; 

     // Wait for next request from client 
     socket.recv (&request); 
     std::memcpy(buf, request.data(), 100); 
     std::cout << "Received message " << buf << std::endl; 

     // Send reply back to client 
     zmq::message_t reply (5); 
     memcpy (reply.data(), "Hello", 5); 
     socket.send (reply); 
    } 
    return 0; 
} 

使用

g++ -std=c++11 -I/home/dev/cppzmq -I/home/dev/libzmq/include receiver.cpp -lzmq -o receiver 

启动过程的时候，一切似乎都做工精细，不出所料，没有休息的接收器输出：

Received message 99996 
Received message 99997 
Received message 99998 
Received message 99999 
Received message done 

但我所期待的：看看netstat的：

netstat 
Active Internet connections (w/o servers) 
Proto Recv-Q Send-Q Local Address   Foreign Address   State  
tcp  0  0 localhost:38345   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:46228   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:60309   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:46916   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:47600   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:54454   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:46409   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:51142   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:40355   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:40005   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:45614   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:48974   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:41427   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:58740   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:58754   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:60044   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:57478   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:50419   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:44361   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:37284   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:38662   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:45968   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:57407   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:59200   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:41292   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:55243   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:51489   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:48865   localhost:5555   TIME_WAIT 
tcp  0  0 localhost:35491   localhost:5555   TIME_WAIT 
... 

一次运行后，我有超过20k（！）个这样的插槽，处于TIME_WAIT状态。这是因为中socket的变化范围void send(...)。我不清楚zmq在超出范围时销毁套接字时会做什么，但我确定它将在套接字的fd上调用close()，这将使您的套接字处于TIME_WAIT状态。即使我的发送者和接收者运行顺利，我也不知道你的系统如何处理这么多的套接字。另外，我不知道你的zhelpers.h文件在做什么。但是我知道，如果将套接字置于全局范围内，则在一个套接字上的发送方只会发生一次close（）调用。我会从这里开始调查更多。也许，看看how-to-forcibly-close-a-socket-in-time-wait ...