对象中的Python多处理

普克

我正在编写一个程序,其中可变数量的Agent对象同时运行多个串行方法,并将它们的返回值存储在queue属性中。每个代理都具有单个Worker(Process的子类)作为属性,并为其提供作业以通过cmd_queue串行运行。代理在res_queue中从其Worker获取结果。这些是当前的Manager()。Queue()实例,其原因是:TypeError: Pickling an AuthenticationString object is disallowed for security reasons但是,如果我使用常规的Queue.Queue,则工作线程会获得代理的cmd_queue的副本,并且看不到代理向其添加的内容(始终为空)。

我可以使用此问题中引用的解决方案来腌制实例方法:使用python的multiprocessing Pool.map()时不能腌制<type'instancemethod'>

from multiprocessing import Manager, Process
from time import sleep
import copy_reg  

def _pickle_method(method):
    func_name = method.im_func.__name__
    obj = method.im_self
    cls = method.im_class
    return _unpickle_method, (func_name, obj, cls)

def _unpickle_method(func_name, obj, cls):
    for cls in cls.mro():
        try:
            func = cls.__dict__[func_name]
        except KeyError:
            pass
        else:
            break
    return func.__get__(obj, cls)

copy_reg.pickle(types.MethodType, _pickle_method, _unpickle_method  

class Worker(Process):
    def __init__(self, cmd_queue, res_queue):
        self.cmd_queue = cmd_queue
        self.res_queue = res_queue
        Process.__init__(self)

    def run(self):
        while True:
            f, args, kwargs = self.cmd_queue.get()
            self.res_queue.put( f(*args, **kwargs) )  

class Agent:
    def __init__(self):
        self.cmd_queue = Manager().Queue()
        self.res_queue = Manager().Queue()
        self.worker = Worker(self.cmd_queue, self.res_queue)
        self.worker.start()

    def produce(self, f, *args, **kwargs):
        self.cmd_queue.put((f, args, kwargs))

    def do_some_work(self):
        self.produce(self.foo, waka='waka')

    def do_some_other_work(self):
        self.produce(self.bar, humana='humana')

    def foo(self, **kwargs):
        sleep(5)
        return('this is a foo')

    def bar(self, **kwargs):
        sleep(10)
        return('this is a bar')

    def get_results(self):  #blocking call
        res = []
        while not self.cmd_queue.empty():#wait for Worker to finish
            sleep(.5)
        while not self.res_queue.empty():
            res.append(self.res_queue.get())
        return res  

#This is the interface I'm looking for.
if __name__=='__main__':
    agents = [Agent() for i in range(50)]
    #this should flow quickly as the calls are added to cmd_queues
    for agent in agents:        
        agent.do_some_work()
        agent.do_some_other_work()  
    for agent in agents:
        print(agent.get_results())

我的问题是,如何使用多处理程序来使此代码正常工作?或者是否有更好的方法被更广泛接受?这只是较大框架的一小部分,因此我希望它尽可能地面向对象。

编辑:这是在python 2.7中。

损害

您可以使用普通的进行此操作multiprocessing.Queue您只需要调整Agent类,以免Queue在对Agent类本身进行酸洗不对实例进行酸洗。这是必需的,因为Agent当您腌制要发送给的实例方法时,必须腌制实例本身Worker不过,这样做很容易:

class Agent(object): # Agent is now a new-style class
    def __init__(self):
        self.cmd_queue = Queue()
        self.res_queue = Queue()
        self.worker = Worker(self.cmd_queue, self.res_queue)
        self.worker.start()

    def __getstate__(self):
        """ This is called to pickle the instance """
        self_dict = self.__dict__.copy()
        del self_dict['cmd_queue']
        del self_dict['res_queue']
        del self_dict['worker']
        return self_dict

    def __setstate__(self, self_dict):
        """ This is called to unpickle the instance. """
        self.__dict__ = self_dict

    ... # The rest is the same.

请注意,此代码中还有一些其他逻辑问题使它无法正常运行。get_results并没有真正按照您的预期去做,因为这容易受到比赛条件的影响:

    while not self.cmd_queue.empty():#wait for Worker to finish
        sleep(.5)
    while not self.res_queue.empty():
        res.append(self.res_queue.get())

cmd_queue在您实际传递给它的函数在内部完成运行之前,可能(并且确实使用示例代码)最终为空Worker,这意味着当您将所有内容从中拉出时,某些结果将丢失res_queue您可以使用来解决此问题JoinableQueue,它可以使工作人员在完成工作时实际发出信号。

您还应该将哨兵发送给工作进程,以使其正常关闭,并使所有结果都正确地从res_queue进程清除并发送回父进程我还发现我需要在上添加一个哨兵res_queue,否则有时res_queue在从孩子那里写入到它的最后结果实际上在管道中被冲洗之前,在父级中会显示为空,这意味着最后的结果会丢失。

这是一个完整的工作示例:

from multiprocessing import Process, Queue, JoinableQueue
import types
from time import sleep
import copy_reg  

def _pickle_method(method):
    func_name = method.im_func.__name__
    obj = method.im_self
    cls = method.im_class
    return _unpickle_method, (func_name, obj, cls)

def _unpickle_method(func_name, obj, cls):
    for cls in cls.mro():
        try:
            func = cls.__dict__[func_name]
        except KeyError:
            pass
        else:
            break
    return func.__get__(obj, cls)

copy_reg.pickle(types.MethodType, _pickle_method, _unpickle_method)

class Worker(Process):
    def __init__(self, cmd_queue, res_queue):
        self.cmd_queue = cmd_queue
        self.res_queue = res_queue
        Process.__init__(self)

    def run(self):
        for f, args, kwargs in iter(self.cmd_queue.get, 
                                    (None, (), {})): # None is our sentinel
            self.res_queue.put( f(*args, **kwargs) )  
            self.cmd_queue.task_done() # Mark the task as done.
        self.res_queue.put(None) # Send this to indicate no more results are coming
        self.cmd_queue.task_done() # Mark the task as done

class Agent(object):
    def __init__(self):
        self.cmd_queue = JoinableQueue()
        self.res_queue = Queue()
        self.worker = Worker(self.cmd_queue, self.res_queue)
        self.worker.start()

    def __getstate__(self):
        self_dict = self.__dict__.copy()
        del self_dict['cmd_queue']
        del self_dict['res_queue']
        del self_dict['worker']
        return self_dict

    def __setstate__(self, self_dict):
        self.__dict__ = self_dict

    def produce(self, f, *args, **kwargs):
        self.cmd_queue.put((f, args, kwargs))

    def do_some_work(self):
        self.produce(self.foo, waka='waka')

    def do_some_other_work(self):
        self.produce(self.bar, humana='humana')

    def send_sentinel(self):
        self.produce(None)

    def foo(self, **kwargs):
        sleep(2)
        return('this is a foo')

    def bar(self, **kwargs):
        sleep(4)
        return('this is a bar')

    def get_results(self):  #blocking call
        res = []
        self.cmd_queue.join() # This will block until task_done has been called for every put pushed into the queue.
        for out in iter(self.res_queue.get, None):  # None is our sentinel
            res.append(out)
        return res  

#This is the interface I'm looking for.
if __name__=='__main__':
    agents = [Agent() for i in range(50)]
    #this should flow quickly as the calls are added to cmd_queues
    for agent in agents:        
        agent.do_some_work()
        agent.do_some_other_work()  
        agent.send_sentinel()
    for agent in agents:
        print(agent.get_results())

输出:

['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']
['this is a foo', 'this is a bar']

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