@contextlib.contextmanager
def die_on_error():
    try:
        yield
    except Exception:
        logging.error("exception in asynchronous operation",exc_info=True)
        sys.exit(1)
with StackContext(die_on_error):
    # Any exception thrown here *or in callback and its desendents*
    # will cause the process to exit instead of spinning endlessly
    # in the ioloop.
    http_client.fetch(url, callback)
ioloop.start()

AttributeError: 'NoneType' object has no attribute 'do_handshake'

HTTPError: HTTP 599: [Errno 111] Connection refused

import tornado.ioloop
import tornado.httpclient
def handle_request(response):
    if response.error:
        print "Error:", response.error
    else:
        print response.body
    tornado.ioloop.IOLoop.instance().stop()
http_client = tornado.httpclient.AsyncHTTPClient()
http_client.fetch("http://www.hjohj.com/", handle_request)
tornado.ioloop.IOLoop.instance().start()

tornado.httpclient.AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")

if response.error: raise Exception(response.error)

import tornado.ioloop
import tornado.httpclient
def handle_request(response):
    if response.error:
        print "Error:", response.error
    else:
        print response.body
    print 'hello'
    tornado.ioloop.IOLoop.instance().stop()
http_client = tornado.httpclient.AsyncHTTPClient()
http_client.fetch("http://www.hjohj.com/", handle_request)
tornado.ioloop.IOLoop.instance().start()
print 'finish'

WARNING:root:uncaught exception
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/tornado/simple_httpclient.py", line 318, in cleanup
    yield
  File "/usr/local/lib/python2.7/dist-packages/tornado/simple_httpclient.py", line 174, in __init__
    0, 0)
gaierror: [Errno -5] No address associated with hostname
Error: [Errno -5] No address associated with hostname
hello
finish

tornado.simple_httpclient.logging.basicConfig(level = ERROR)