Question

我有一个龙卷风应用程序，我想使用阻塞库来完成某些事情。如果无法以异步方式重写库，那么在龙卷风中执行它的方式是什么？

例如，我希望能够在请求处理程序上放置一个@asynchronous装饰器，在它启动一个长时间运行的函数，它只会在完成后返回响应。我不能只是回电话。最简单的例子当然是什么是正确的睡眠方式10秒而不阻止龙卷风的唯一线程？

Answer 1

看起来我想要的只是创建一个新的线程/进程，并且回调龙卷风的实际行为需要使用IOLoop.instance().add_callback

完成

有更多信息，请here

Answer 2

接受的答案代码是is available on SO。

另一种方法在博文here和a full working gist中详细说明。这是从要点重新发布代码：

from concurrent.futures import ThreadPoolExecutor
from functools import partial, wraps
import time

import tornado.ioloop
import tornado.web


EXECUTOR = ThreadPoolExecutor(max_workers=4)


def unblock(f):

    @tornado.web.asynchronous
    @wraps(f)
    def wrapper(*args, **kwargs):
        self = args[0]

        def callback(future):
            self.write(future.result())
            self.finish()

        EXECUTOR.submit(
            partial(f, *args, **kwargs)
        ).add_done_callback(
            lambda future: tornado.ioloop.IOLoop.instance().add_callback(
                partial(callback, future)))

    return wrapper


class MainHandler(tornado.web.RequestHandler):

    def get(self):
        self.write("Hello, world %s" % time.time())


class SleepHandler(tornado.web.RequestHandler):

    @unblock
    def get(self, n):
        time.sleep(float(n))
        return "Awake! %s" % time.time()


class SleepAsyncHandler(tornado.web.RequestHandler):

    @tornado.web.asynchronous
    def get(self, n):

        def callback(future):
            self.write(future.result())
            self.finish()

        EXECUTOR.submit(
            partial(self.get_, n)
        ).add_done_callback(
            lambda future: tornado.ioloop.IOLoop.instance().add_callback(
                partial(callback, future)))

    def get_(self, n):
        time.sleep(float(n))
        return "Awake! %s" % time.time()


application = tornado.web.Application([
    (r"/", MainHandler),
    (r"/sleep/(\d+)", SleepHandler),
    (r"/sleep_async/(\d+)", SleepAsyncHandler),
])


if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.instance().start()

Answer 3

请尝试以下示例。

import tornado.ioloop
import tornado.web
import time

class MainHandler(tornado.web.RequestHandler):
    @tornado.web.asynchronous
    def get(self, request):
        if request is None:
            self.application.go = False
            self.write("Waiting for GET @ http://localhost:8888/go...<br>")
            self.flush()
            self._do_wait()
        else:
            self.application.go = True
            self.finish('Thanks!')

    def _do_wait(self, timeout_trys=10):
        if self.application.go:
            self.write('Finish')
            self.finish()
        else:
            self.write("Sleeping 2 second, timeout_trys=%s<br>" % timeout_trys)
            self.flush()
            tornado.ioloop.IOLoop.instance().add_timeout(time.time() + 2, 
                lambda: self._do_wait(timeout_trys-1))


application = tornado.web.Application([
    (r"/(\w+)?", MainHandler),
])

if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.instance().start()

在Tornado中运行阻止代码

3 个答案: