I/O error(socket error): [Errno 111] Connection refused

问题:

I have a program that uses urllib to periodically fetch a url, and I see intermittent errors like :

I/O error(socket error): [Errno 111] Connection refused.

It works 90% of the time, but the othe r10% it fails. If retry the fetch immediately after it fails, it succeeds. I'm unable to figure out why this is so. I tried to see if any ports are available, and they are. Any debugging ideas?

For additional info, the stack trace is:

File "/usr/lib/python2.6/urllib.py", line 203, in open      return getattr(self, name)(url)  File "/usr/lib/python2.6/urllib.py", line 342, in open_http     h.endheaders()  File "/usr/lib/python2.6/httplib.py", line 868, in endheaders     self._send_output()  File "/usr/lib/python2.6/httplib.py", line 740, in _send_output     self.send(msg)  File "/usr/lib/python2.6/httplib.py", line 699, in send     self.connect()  File "/usr/lib/python2.6/httplib.py", line 683, in connect     self.timeout)  File "/usr/lib/python2.6/socket.py", line 512, in create_connection     raise error, msg 

Edit - A google search isn't very helpful, what I got out of it is that the server I'm fetching from sometimes refuses connections, how can I verify its not a bug in my code and this is indeed the case?

回答1:

Use a packet sniffer like Wireshark to look at what happens. You need to see a SYN-flagged packet outgoing, a SYN+ACK-flagged incoming and then a ACK-flagged outgoing. After that, the port is considered open on the local side.

If you only see the first packet and the error message comes after several seconds of waiting, the other side is not answering at all (like in: unplugged cable, overloaded server, misguided packet was discarded) and your local network stack aborts the connection attempt. If you see RST packets, the host actually denies the connection. If you see "ICMP Port unreachable" or host unreachable packets, a firewall or the target host inform you of the port actually being closed.

Of course you cannot expect the service to be available at all times (consider all the points of failure in between you and the data), so you should try again later.

回答2:

Getting an ECONNREFUSED errno means that your kernel was refused a connection at the other end, so if it's a bug, it's either in your kernel or in the other end. What you can do is to trap the error in a very specific way and try again in a little while, since this seems to work:

# This is Python > 2.5 code import errno, time  for attempt in range(MAXIMUM_NUMBER_OF_ATTEMPTS):     try:         # your urllib call here     except EnvironmentError as exc: # replace " as " with ", " for Python<2.6         if exc.errno == errno.ECONNREFUSED:             time.sleep(A_COUPLE_OF_SECONDS)         else:             raise # re-raise otherwise     else: # we tried, and we had no failure, so         break else: # we never broke out of the for loop     raise RuntimeError("maximum number of unsuccessful attempts reached") 

Replace the two all-caps constants with your favourite numbers.

回答3:

I previously had this problem with my EC2 instance (I was serving couchdb to serve resources -- am considering Amazon's S3 for the future).

One thing to check (assuming Ec2) is that the couchdb port is added to your open ports within your security policy.

I specifically encountered

"[Errno 111] Connection refused"

over EC2 when the instance was stopped and started. The problem seems to be a pidfile race. The solution for me was killing couchdb (entirely and properly) via:

pkill -f couchdb 

and then restarting with:

/etc/init.d/couchdb restart 

回答4:

I'm not exactly sure what's causing this. You can try looking in your socket.py (mine is a different version, so line numbers from the trace don't match, and I'm afraid some other details might not match as well).

Anyway, it seems like a good practice to put your url fetching code in a try: ... except: ... block, and handle this with a short pause and a retry. The URL you're trying to fetch may be down, or too loaded, and that's stuff you'll only be able to handle in with a retry anyway.

回答5:

Its seems that server is not running properly so ensure that with terminal by

telnet ip port 

example

telnet localhost 8069 

It will return connected to localhost so it indicates that there is no problem with the connection Else it will return Connection refused it indicates that there is problem with the connection

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