Question

I need to connect to a server (e.g. smpp server) and send periodic data every 2 seconds, here’s the code:

import asyncore, socket, threading, time

class SClient(asyncore.dispatcher):
    buffer = ""
    t = None

    def __init__(self, host):
        asyncore.dispatcher.__init__(self)
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connect( (host, 25) )

        print "sending data from __init__"
        self.sendCommand("data_init")
        self.t = SenderThread(self)
        self.t.start()

    def sendCommand(self, command):
        self.buffer = command

    def handle_close(self):
        self.close()
        self.t.stop()

    def handle_read(self):
        print self.recv(8192)

    def writable(self):
        print 'asking for writable ? len='+str(len(self.buffer))
        return (len(self.buffer) > 0)

    def handle_write(self):
        print "writing to socket"
        sent = self.send(self.buffer)
        self.buffer = self.buffer[sent:]
        print "wrote "+str(sent)+" to socket"

class SenderThread(threading.Thread):
    _stop = False

    def __init__(self, client):
        super(SenderThread,self).__init__()
        self.client = client

    def stop(self):
        self._stop = True

    def run(self):
        counter = 0
        while self._stop == False:
            counter += 1
            time.sleep(1)
            if counter == 2:
                print "sending data from thread"
                self.client.sendCommand("data_thread")
                counter = 0

client = SClient('127.0.0.1')
asyncore.loop()

Here’s the output when running:

$ python test.py 
sending data from __init__
asking for writable ? len=9
writing to socket
wrote 9 to socket
asking for writable ? len=0
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
asking for writable ? len=11
writing to socket
wrote 11 to socket
asking for writable ? len=0
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
asking for writable ? len=11
writing to socket
wrote 11 to socket
asking for writable ? len=0
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread
sending data from thread

My thread is sending data to server every 2 seconds through the buffer variable but asyncore is calling writable and handle_write exactly every 1 minute, i dont understand why it doesnt fetch the buffer just after its getting populated from the thread ?

Answer 1

Look at the docs for the asyncore loop method.

The timeout argument sets the timeout parameter for the appropriate
select() or poll() call, measured in seconds; the default is 30
seconds.

It’s only firing the handle_write every 30 secs.