python - 在这种情况下如何使用 Tornado 协程？

Question

我创建了 tornado 服务器，它接受 python 和 matlab 代码并执行它。这是服务器代码。

from zmq.eventloop.zmqstream import ZMQStream
from zmq.eventloop import ioloop
ioloop.install()

from functools import partial
from tornado import web, gen, escape
from tornado import options, httpserver
from tornado.concurrent import Future

settings = dict()
settings['autoreload'] = True 
settings['debug'] = True

from jupyter_client import MultiKernelManager

reply_futures = {}
kids = []

class MainHandler(web.RequestHandler):
    def get(self):
        self.write("Hello")

class ExecuteHandler(web.RequestHandler):
    def get(self):
        self.write("approaching execute")

    def post(self):
        data = escape.json_decode(self.request.body)
        print data
        self.application.execute_code(data)

class Application(web.Application):

    def __init__(self):

        handlers = []
        handlers.append((r"/", MainHandler))
        handlers.append((r"/execute", ExecuteHandler))
        web.Application.__init__(self, handlers, **settings)
        self.km = MultiKernelManager()
        self.setup_kernels()

    def setup_kernels(self):

        matlab_kernel_id = self.km.start_kernel(kernel_name="matlab")
        python_kernel_id = self.km.start_kernel(kernel_name="python")

        self.matlab_kernel_id = matlab_kernel_id
        self.python_kernel_id = python_kernel_id

        matkab_kernel_client = self.km.get_kernel(matlab_kernel_id).client()
        matkab_kernel_client.start_channels()

        python_kernel_client = self.km.get_kernel(python_kernel_id).client()
        python_kernel_client.start_channels()

        self.matkab_kernel_client = matkab_kernel_client
        self.python_kernel_client = python_kernel_client

        matlab_iopub_stream = ZMQStream(matkab_kernel_client.iopub_channel.socket)
        matlab_shell_stream = ZMQStream(matkab_kernel_client.shell_channel.socket)

        python_iopub_stream = ZMQStream(python_kernel_client.iopub_channel.socket)
        python_shell_stream = ZMQStream(python_kernel_client.shell_channel.socket)

        matlab_iopub_stream.on_recv_stream(partial(self.reply_callback, matkab_kernel_client.session))
        matlab_shell_stream.on_recv_stream(partial(self.reply_callback, matkab_kernel_client.session))

        python_iopub_stream.on_recv_stream(partial(self.reply_callback, python_kernel_client.session))
        python_shell_stream.on_recv_stream(partial(self.reply_callback, python_kernel_client.session))

    def reply_callback(self, session, stream, msg_list):
        idents, msg_parts = session.feed_identities(msg_list)
        reply = session.deserialize(msg_parts)

        if "stream" == reply["msg_type"]:
            print reply["content"]["text"]
        parent_id = reply['parent_header'].get('msg_id')
        reply_future = reply_futures.get(parent_id)
        if reply_future:
            reply_future.set_result(reply)

    def execute_code(self, data):

        matlab_code = data['matlab_code']
        python_code = data['python_code']

        self.execute_matlab_then_python(matlab_code, python_code)

    @gen.coroutine
    def execute_matlab_then_python(self, matlab_code, python_code):

        print "executing matlab code"
        parent_id1 = self.matkab_kernel_client.execute(matlab_code)
        f1 = reply_futures[parent_id1] = Future()
        yield f1    

        print "executing python code"
        parent_id2 = self.python_kernel_client.execute(python_code)
        f2 = reply_futures[parent_id2] = Future()
        yield f2

    def shutdown_kernels(self):
        self.km.get_kernel(self.matlab_kernel_id).cleanup_connection_file()
        self.km.shutdown_kernel(self.matlab_kernel_id)

        self.km.get_kernel(self.python_kernel_id).cleanup_connection_file()
        self.km.shutdown_kernel(self.python_kernel_id)

if __name__ == '__main__':

    options.parse_command_line()
    app = Application()
    server = httpserver.HTTPServer(app)
    server.listen(8888)

    try:
        ioloop.IOLoop.current().start()
    except KeyboardInterrupt:
        print 'going down'
    finally:    
        app.shutdown_kernels()

我用来访问的客户端代码在这里

import json
import requests

matlab_code = "a=magic(3);disp(a)"
python_code = "print 'Hello World!!'"

data = {}
data['matlab_code'] = matlab_code
data['python_code'] = python_code

r = requests.post('http://0.0.0.0:8888/execute', json.dumps(data))

我关心的是保持执行顺序，这样 python 代码只在 matlab 完成后才执行。我正在使用 jupyter_client 来执行 matlab/python 代码。我在这里使用 python27。问题是当我提交代码时它抛出 TypeError: 'NoneType' object is not iterable。这是它的堆栈跟踪。

[E 160809 15:17:51 ioloop:633] Exception in callback None    Traceback (most recent call last):      File "/usr/local/lib/python2.7/dist-packages/tornado/ioloop.py", line 887, in start        handler_func(fd_obj, events)      File "/usr/local/lib/python2.7/dist-packages/tornado/stack_context.py", line 275, in null_wrapper        return fn(*args, **kwargs)      File "/usr/local/lib/python2.7/dist-packages/zmq/eventloop/zmqstream.py", line 440, in _handle_events        self._handle_recv()      File "/usr/local/lib/python2.7/dist-packages/zmq/eventloop/zmqstream.py", line 472, in _handle_recv        self._run_callback(callback, msg)      File "/usr/local/lib/python2.7/dist-packages/zmq/eventloop/zmqstream.py", line 414, in _run_callback        callback(*args, **kwargs)      File "/usr/local/lib/python2.7/dist-packages/tornado/stack_context.py", line 275, in null_wrapper        return fn(*args, **kwargs)      File "/usr/local/lib/python2.7/dist-packages/zmq/eventloop/zmqstream.py", line 191, in         self.on_recv(lambda msg: callback(self, msg), copy=copy)      File "tornado_test.py", line 86, in reply_callback        reply_future.set_result(reply)      File "/usr/local/lib/python2.7/dist-packages/tornado/concurrent.py", line 276, in set_result        self._set_done()      File "/usr/local/lib/python2.7/dist-packages/tornado/concurrent.py", line 320, in _set_done        for cb in self._callbacks:    TypeError: 'NoneType' object is not iterable

我不明白这里有什么问题？

Answer 1

不幸的是，神秘的错误消息“'NoneType' 对象不可迭代”意味着您在同一 Future 对象上多次调用 set_result。我不太了解 zmq 或 jupyter 内核接口(interface)，但我的猜测是两个不同内核的 execute 方法返回的 ID 重叠，或者你得到的不止一个每次执行调用的响应(来自两个不同的流？)。