python - 如何让多个 gevent 服务器永远服务？

Question

目前，我的应用程序有两个服务器:第一个服务器处理订单并单独响应，第二个服务器将结果广播给其他感兴趣的订阅者。它们需要从不同的港口提供服务。我可以 start() 两者，但我只能将其中一个调用到serve_forever()，因为我读到它是一个阻塞函数。我正在寻找有关如何防止两台服务器退出的想法。缩写代码如下:

def main():
    stacklist = []
    subslist = []
    stacklist.append(CreateStack('stuff'))
    subslist.append(Subscription('stuff'))
    bcastserver = BroadcastServer(subslist) # creates a new server
    tradeserver = TradeServer(stacklist) # creates a new server
    bcastserver.start() # start accepting new connections
    tradeserver.start() # start accepting new connections
    #bcastserver.serve_forever()  #if I do it here, the first one...
    #tradeserver.serve_forever()  #blocks the second one

class TradeServer(StreamServer):
    def __init__(self, stacklist):
        self.stacklist = stacklist
        StreamServer.__init__(self, ('localhost', 12345), self.handle)
        #self.serve_forever()  #If I put it here in both, neither works

    def handle(self, socket, address):
        #handler here

class BroadcastServer(StreamServer):
    def __init__(self, subslist):
        StreamServer.__init__(self, ('localhost', 8000), self.handle)
        self.subslist = subslist
        #self.serve_forever()  #If I put it here in both, neither works

    def handle(self, socket, address):
        #handler here

也许我只是需要一种方法来防止两者退出，但我不确定如何做。最后，我希望两台服务器永远监听传入连接并处理它们。

Answer 1

我知道这个问题有一个公认的答案，但还有一个更好的答案。我添加它是为了像我这样稍后找到这篇文章的人。

如 gevent documentation about servers 中所述:

The BaseServer.serve_forever() method calls BaseServer.start() and then waits until interrupted or until the server is stopped.

所以你可以这样做:

def main():
    stacklist = []
    subslist = []
    stacklist.append(CreateStack('stuff'))
    subslist.append(Subscription('stuff'))
    bcastserver = BroadcastServer(subslist) # creates a new server
    tradeserver = TradeServer(stacklist) # creates a new server
    bcastserver.start() # starts accepting bcast connections and returns
    tradeserver.serve_forever() # starts accepting trade connections and blocks until tradeserver stops
    bcastserver.stop() # stops also the bcast server

gevent introduction documentation解释了为什么它有效:

Unlike other network libraries, though in a similar fashion as eventlet, gevent starts the event loop implicitly in a dedicated greenlet. There’s no reactor that you must call a run() or dispatch() function on. When a function from gevent’s API wants to block, it obtains the gevent.hub.Hub instance — a special greenlet that runs the event loop — and switches to it (it is said that the greenlet yielded control to the Hub).

当serve_forever()阻塞时，它不会阻止任一服务器继续通信。

注意:在上面的代码中，交易服务器是决定整个应用程序何时停止的服务器。如果您希望广播服务器决定这一点，则应该在 start() 和 serve_forever() 调用中交换它们。