I O error socket error Errno 111 Connection refused

Question

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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  gt  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 lt 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

User · Answer

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

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

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