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python - 使用 Tornado 发出同步请求。RuntimeError：在另一个循环正在运行时无法运行事件循环

问题描述

我正在尝试使用 Tornado 发出同步请求。
试图进行 API 调用。

主文件

import tornado.web
import tornado.httpserver
import tornado.options
import tornado.ioloop
from tornado.web import url

from handlers import IndexHandler

from tornado.options import define, options
define("port", default=8000, help="run on the given port", type=int)

if __name__ == "__main__":
    tornado.options.parse_command_line()
    app = tornado.web.Application(
        handlers=[
            url(r"/", IndexHandler),
        ]
    )
    http_server = tornado.httpserver.HTTPServer(app)
    http_server.listen(options.port)
    tornado.ioloop.IOLoop.instance().start()

我的 handlers.py 是...

import tornado.web
import tornado.httpclient

import urllib
import json
import datetime
import time

class IndexHandler(tornado.web.RequestHandler):
    def get(self):
        query = self.get_argument('q')
        client = tornado.httpclient.HTTPClient()
        response = client.fetch("https://pokeapi.co/api/v2/pokemon/" + urllib.urlencode(("query")))
        print(response)
        if response == "Not Found":
            self.write("Invalid Input")
        response_data = json.loads(response.body)
        pikachu_name = response_data['name']
        pikachu_order = response_data['order']
        self.write("""
            Pickachu Name: %s <br>
            Pickachu Order: %d <br>
            """ %(pikachu_name, pikachu_order))

现在我面临的问题是 

[E 200407 02:18:37 web:1792] Uncaught exception GET /?q=pikachu (::1)
    HTTPServerRequest(protocol='http', host='localhost:8000', method='GET', uri='/?q=pikachu', version='HTTP/1.1', remote_ip='::1')
    Traceback (most recent call last):
      File "C:\Python\Python37\lib\site-packages\tornado\web.py", line 1701, in _execute
        result = method(*self.path_args, **self.path_kwargs)
      File "C:\Users\Bagga\Documents\tornado\Tweet Rate\handlers.py", line 12, in get
        client = tornado.httpclient.HTTPClient()
      File "C:\Python\Python37\lib\site-packages\tornado\httpclient.py", line 107, in __init__
        self._async_client = self._io_loop.run_sync(make_client)
      File "C:\Python\Python37\lib\site-packages\tornado\ioloop.py", line 526, in run_sync
        self.start()
      File "C:\Python\Python37\lib\site-packages\tornado\platform\asyncio.py", line 149, in start
        self.asyncio_loop.run_forever()
      File "C:\Python\Python37\lib\asyncio\base_events.py", line 529, in run_forever
        'Cannot run the event loop while another loop is running')
    RuntimeError: Cannot run the event loop while another loop is running
[E 200407 02:18:37 web:2250] 500 GET /?q=pikachu (::1) 55.85ms

问题是什么，我该如何解决？
我在这里可以看到的主要错误是，
RuntimeError: Cannot run the event loop while another loop is running
我觉得这是由于 IOLoop 和 HTTPClient，但不明白是什么问题？

标签： pythonwebfetchtornadosynchronous

解决方案

我引用的文档HTTPClient

在 5.0 版更改: 由于 asyncio 的限制，在 IOLoop 运行时不再可能使用同步 HTTPClient。请改用 AsyncHTTPClient。

请AsyncHTTPClient改用。

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