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    <p>The Queue's get method is really blocking. Using it with timeout could potentially solve your problem, but it definitely won't be a cleanest solution and, which is the most important, will introduce extra latency for no good reason. Even if it wasn't blocking, that won't be a good solution either. Just because non-blocking itself is not enough, the good asynchronous call/API should smoothly integrate into the I/O framework in use. Be that gevent for Python, libevent for C or Boost ASIO for C++.</p> <p>The easiest solution would be to use simple I/O by spawning your console applications and attaching to its console in and out descriptors. There are at two major factors to consider:</p> <ul> <li>It will be extremely easy for your clients to write client applications. They will not have to work with any kind of IPC, socket or other code, which could be very hard thing for many. With this approach, application will just read from stdin and write to stdout.</li> <li>It will be extremely easy to test console applications using this approach as you can manually start them, enter text into console and see results.</li> <li>Gevent is a perfect fit for async read/write here.</li> </ul> <p>However, the downside is that you will have to start this application, there will be no support for concurrent communication with it, and there will be no support for communication over network. There is even a <a href="https://bitbucket.org/denis/gevent/src/23fd80c3be00/examples/processes.py" rel="nofollow">good example for starters</a>.</p> <p>To keep it simple but more flexible, you can use TCP/IP sockets. If both client and server are running on the same machine. Also, a good operating system will use IPC as an underlying implementation, so it will be fast. And, if you are worrying about performance of this case, you probably should not use Python at all and look at other technologies.</p> <p>Even fancies solution – use <a href="http://www.zeroc.com/" rel="nofollow">ZeroC ICE</a>. It is very modern technology allowing almost seamless inter-process communication. It is a CORBA killer, very easy to use. It is heavily used by many, proven to be fastest in its class and rock stable. The beauty of this solution is that you can seamlessly integrate programs in many different languages, like Python, Java, C++ etc. But this will require some of your time to get familiar with a concept. If you decide to go this way, just spend a day reading trough documentation.</p> <p>Hope it helps. Good luck!</p>
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    1. COThank you for answering in detail. The problem with the gevent processes.py example is, that it implements only a single communication step. We are using a worker which can send data anytime and we can send commands to it in the meantime, like the stop command. But it won't terminate the subprocess, it should remain usable. I'll try to integrate the two loops, however. It might not help on Windows, but worth a try. Using TCP/IP is another option I was thinking about, but it would need a wrapper layer, which complicates things and make the solution heavy weight. I'll take a look at ZeroC ICE.
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    2. CO@fviktor: You are welcome. You can send data anytime using async I/O. The only thing you will have to guarantee is that you will not perform multiple writes in parallel. Dedicated writer thread & some queue helps in this case.
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