似乎 XPUB/XSUB 套接字类型有一个很难解决的严重缺陷:
这是我对该中心节点的实现:
#include <zmq.hpp>
int main()
{
zmq::context_t context(1);
//Incoming publications come here
zmq::socket_t sub(context, ZMQ_XSUB);
sub.bind("ipc://subscriber.ipc");
//Outgoing publications go out through here.
zmq::socket_t pub(context, ZMQ_XPUB);
pub.bind("ipc://publisher.ipc");
zmq::proxy(sub, pub, nullptr);
return 0;
}
当然,问题是慢工综合症。如果我将一个新发布者连接到 XSUB 并发布一些消息,它们就会消失在空白中:
#include "zhelpers.hpp"
int main () {
// Prepare our context and publisher
zmq::context_t context(1);
zmq::socket_t publisher(context, ZMQ_PUB);
publisher.connect("ipc://subscriber.ipc");
s_sendmore (publisher, "B");
s_send (publisher, "Disappears into the void!!");
return 0;
}
但是,如果我在连接到 XSUB 后 sleep(1)
,它会神奇地工作:
#include "zhelpers.hpp"
int main () {
// Prepare our context and publisher
zmq::context_t context(1);
zmq::socket_t publisher(context, ZMQ_PUB);
publisher.connect("ipc://subscriber.ipc");
sleep(1);
s_sendmore (publisher, "B");
s_send (publisher, "Magically works!!");
return 0;
}
该指南声称有一个简单的解决方案来解决这种“慢连接”综合症,但从未提供有效的同步 XSUB/XPUB 实现。经过大量搜索,看起来大多数人只是在 sleep
,这真的很糟糕。
为什么这个问题一直没有被修复?有任何已知的解决方法吗?我所有的谷歌查询都让我回到指南...
最佳答案
我找到了一种解决方法 here ,也就是在发布端使用PUSH/PULL,在订阅端使用PUB/SUB。新拓扑如下所示:
这是中心节点所需的代码:
#include <zmq.hpp>
int main()
{
zmq::context_t context(1);
//Incoming publications come here
zmq::socket_t sub(context, ZMQ_PULL);
sub.bind("ipc://subscriber.ipc");
//Outgoing publications go out through here.
zmq::socket_t pub(context, ZMQ_PUB);
pub.bind("ipc://publisher.ipc");
zmq::proxy(sub, pub, nullptr);
return 0;
}
然后对于发布商:
#include "zhelpers.hpp"
int main () {
// Prepare our context and publisher
zmq::context_t context(1);
zmq::socket_t publisher(context, ZMQ_PUSH);
publisher.connect("ipc://subscriber.ipc");
s_sendmore (publisher, "B");
s_send (publisher, "No sleep!");
return 0;
}
此解决方案似乎运行良好,我希望人们在看到它的任何缺点时提出意见。如果我遇到更好的答案,我会在这里发布。
关于c++ - ZeroMQ XPUB/XSUB 严重缺陷?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43129714/