Process communication in Python

What is the best way to establish communication between two processes in python? After some googling, I tried to do so:

parent_pipe, child_pipe = Pipe()
p = Process(target = instance_tuple.instance.run(), \
    args = (parent_pipe, child_pipe,))
p.start()

Sending data to the child process:

command = Command(command_name, args)
parent_pipe.send(command)

Process target function:

while True:
    if (self.parent_pipe.poll()):
        command = parent_pipe.recv()
        if (command.name == 'init_model'):
            self.init_model()
        elif (command.name == 'get_tree'):
            tree = self.get_fidesys_tree(*command.args)
            result = CommandResult(command.name, tree)
            self.child_pipe.send(result)
        elif(command.name == 'set_variable'):
            name = command.args[0]
            value = command.args[1]
   开发者_C百科         self.config[name] = value

But it doesn't seem to work (child process doesn't receive anything through parent_pipe). How can I fix it?

Thanks in advance.

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You can have a look here : http://docs.python.org/library/multiprocessing.html#exchanging-objects-between-processes The solution is close to yours but seems easier.

---

If I understand the documentation, in child process you should read from the child part of the pipe.

# Process Target function

while True:
        # poll(None) because you don't want to go through the loop fast between commands
        if (self.child_pipe.poll(None)):    
            command = child_pipe.recv()
            if (command.name == 'init_model'):
                self.init_model()
            elif (command.name == 'get_tree'):
                tree = self.get_fidesys_tree(*command.args)
                result = CommandResult(command.name, tree)
                self.child_pipe.send(result)
            elif(command.name == 'set_variable'):
                name = command.args[0]
                value = command.args[1]
                self.config[name] = value