Question

在我的Python Twisted应用程序中，我需要从客户端接收数据，执行一些数据库操作，并且 - 依赖于数据 - 在单独的线程中运行一些阻塞代码。

到目前为止，我有：

d = get_user(user_id)

d.addCallback(do_something_with_input_data, input_data)
d.addCallback(run_blocking_code)
d.addCallback(save_data_into_db)
d.addCallback(response_to_client)

@defer.inlineCallbacks
def get_user(self, user_id):
    user = yield get_user_from_db(user_id)
    defer.returnValue(user)

def do_something_with_input_data(user, input_data):
    # do smth...
    return results

@defer.inlineCallbacks
def run_blocking_code(results)

    threads.deferToThread(run_in_separate_thread, results)
    return results

@defer.inlineCallbacks
def save_data_into_db(results)
    yield save_in_db(results)
    def.returnValue('OK')

def response_to_client(response)
    # send 'OK' to client

这是一个很好的方法来调用deferToThread()中的run_blocking_code()吗？如果是这样，我如何让save_data_into_db()等到线程结束？

Answer 1

我说一般概念很好。我添加了一些errbacks，您还需要调整run_blocking_code函数：

from twisted.internet import defer, threads

@defer.inlineCallbacks
def run_blocking_code(results):

    # the `deferToThread` returns a deferred
    d = threads.deferToThread(run_in_separate_thread, results)

    # let's wait for it here (need a yield for functions decorated with `inlineCallbacks`)
    yield d

    # now return its value to the next function in the callback chain
    defer.returnValue(d.result)

混合Deferred和deferToThread以在单独的线程中运行阻塞代码

1 个答案: