Question

当我尝试按照pyzmq official documentation中的描述组合Tornado和pyzmq ioloops时，我遇到了一个恼人的（虽然不是关键）问题。

我有一个运行tornado（T）服务器的进程，该服务器接受来自客户端（C）的REST API请求，并通过ZMQ传输到另一个执行实际工作的进程（Z）来代理它们。

C <-> T <-> Z

如果C在 Z回复T之前关闭连接，则Z（龙卷风）会输出一长串异常跟踪（参见底部）。想象一下以下示例：

import tornado.ioloop from tornado.web import Application, RequestHandler, asynchronous from zmq.eventloop import ioloop import time def time_consuming_task(): time.sleep(5) class TestHandler(RequestHandler): def get(self, arg): print "Test arg", arg time_consuming_task() print "Ok, time to reply" self.write("Reply") if __name__ == "__main__": app = tornado.web.Application( [ (r"/test/([0-9]+)", TestHandler) ]) ioloop.install() app.listen(8080) tornado.ioloop.IOLoop.instance().start()

这个例子实际上并没有与任何ZMQ对等对话，它只是将pyzmq ioloop附加到龙卷风的ioloop上。虽然，这足以说明问题。

从控制台一台运行服务器：

% python example.py

从控制台两个运行客户端并在服务器回复之前中断它（即在5秒内）：

% curl -is http://localhost:8080/test/1 ^C

服务器的输出是：

Test arg 1 Ok, time to reply WARNING:root:Read error on 24: [Errno 54] Connection reset by peer ERROR:root:Uncaught exception GET /test/1 (::1) HTTPRequest(protocol='http', host='localhost:8080', method='GET', uri='/test/1', version='HTTP/1.1', remote_ip='::1', body='', headers={'Host': 'localhost:8080', 'Accept': '*/*', 'User-Agent': 'curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8r zlib/1.2.5'}) Traceback (most recent call last): File "/Library/Python/2.7/site-packages/tornado/web.py", line 1023, in _execute self.finish() File "/Library/Python/2.7/site-packages/tornado/web.py", line 701, in finish self.request.finish() File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 433, in finish self.connection.finish() File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 187, in finish self._finish_request() File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 223, in _finish_request self.stream.read_until(b("\r\n\r\n"), self._header_callback) File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 153, in read_until self._try_inline_read() File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 386, in _try_inline_read if self._read_to_buffer() == 0: File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 421, in _read_to_buffer chunk = self._read_from_socket() File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 402, in _read_from_socket chunk = self.socket.recv(self.read_chunk_size) error: [Errno 54] Connection reset by peer ERROR:root:Cannot send error response after headers written ERROR:root:Uncaught exception, closing connection. Traceback (most recent call last): File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 304, in wrapper callback(*args) File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 262, in _on_headers self.request_callback(self._request) File "/Library/Python/2.7/site-packages/tornado/web.py", line 1412, in __call__ handler._execute(transforms, *args, **kwargs) File "/Library/Python/2.7/site-packages/tornado/web.py", line 1025, in _execute self._handle_request_exception(e) File "/Library/Python/2.7/site-packages/tornado/web.py", line 1065, in _handle_request_exception self.send_error(500, exc_info=sys.exc_info()) File "/Library/Python/2.7/site-packages/tornado/web.py", line 720, in send_error self.finish() File "/Library/Python/2.7/site-packages/tornado/web.py", line 700, in finish self.flush(include_footers=True) File "/Library/Python/2.7/site-packages/tornado/web.py", line 660, in flush self.request.write(headers + chunk, callback=callback) File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 429, in write self.connection.write(chunk, callback=callback) File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 177, in write assert self._request, "Request closed" AssertionError: Request closed ERROR:root:Exception in callback Traceback (most recent call last): File "/Library/Python/2.7/site-packages/pyzmq-2.2.0-py2.7-macosx-10.7-intel.egg/zmq/eventloop/ioloop.py", line 434, in _run_callback callback() File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 304, in wrapper callback(*args) File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 262, in _on_headers self.request_callback(self._request) File "/Library/Python/2.7/site-packages/tornado/web.py", line 1412, in __call__ handler._execute(transforms, *args, **kwargs) File "/Library/Python/2.7/site-packages/tornado/web.py", line 1025, in _execute self._handle_request_exception(e) File "/Library/Python/2.7/site-packages/tornado/web.py", line 1065, in _handle_request_exception self.send_error(500, exc_info=sys.exc_info()) File "/Library/Python/2.7/site-packages/tornado/web.py", line 720, in send_error self.finish() File "/Library/Python/2.7/site-packages/tornado/web.py", line 700, in finish self.flush(include_footers=True) File "/Library/Python/2.7/site-packages/tornado/web.py", line 660, in flush self.request.write(headers + chunk, callback=callback) File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 429, in write self.connection.write(chunk, callback=callback) File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 177, in write assert self._request, "Request closed" AssertionError: Request closed

注意：这似乎是与pyzmq相关的问题，因为在排除pyzmq ioloop后消失了。

服务器不会死，它可以被其他客户端使用，因此问题并不重要。但是，在日志文件中找到这些巨大的混乱痕迹非常烦人。

那么，有没有任何众所周知的方法来解决这个问题？感谢。

Answer 1

这不是ZMQ问题。除超时原因外，可以关闭请求。 ZMQ这里唯一的问题是他们提出AssertionError，这是常见的，而不是更具体的例外。

如果您确定，您不希望在日志文件中出现这些异常 - 请执行以下操作：

try: 
    time_consuming_task()
except AssertionError as e:
    if e.message == 'Request closed': 
        logging.info('Bad, annoying client, came to us again!') 
    else:
        raise e

结合龙卷风和zmq ioloops：通过对等异常重置连接

1 个答案: