Handling a timeout error in python sockets

Question

I am trying to figure out how to use the try and except to handle a socket timeout    from socket import    def main        client socket   socket AF INET SOCK DGRAM      client socket settimeout 1      server host    localhost      server port   1234     while True           client socket sendto  Message   server host server port           try              reply  server address info   client socket recvfrom 1024              print reply         except socket Timeouterror               more code   The way I added the socket module was to import everything  but how do I handle exceptions in the docs it says you can use socket timeouterror  but that doesn t work for me   Also  how would I write the try exception block if I did import socket  Can someone also explain the difference in the imports

User · Answer

When you do from socket import   python is loading a socket module to the current namespace  Thus you can use module s members as if they are defined within your current python module   When you do import socket  a module is loaded in a separate namespace  When you are accessing its members  you should prefix them with a module name  For example  if you want to refer to a socket class  you will need to write client socket   socket socket socket AF INET socket SOCK DGRAM    As for the problem with timeout - all you need to do is to change except socket Timeouterror  to except timeout   since timeout class is defined inside socket module and you have imported all its members to your namespace

User · Answer

from foo import      adds all the names without leading underscores  or only the names defined in the modules   all   attribute  in foo into your current module   In the above code with from socket import   you just want to catch timeout as you ve pulled timeout into your current namespace     from socket import   pulls in the definitions of everything inside of socket but doesn t add socket itself   try        socketstuff except timeout      print  caught a timeout    Many people consider import   problematic and try to avoid it   This is because common variable names in 2 or more modules that are imported in this way will clobber one another   For example  consider the following three python files     a py def foo        print  this is a s foo function     b py def foo        print  this is b s foo function     yourcode py from a import   from b import   foo     If you run yourcode py you ll see just the output  this is b s foo function      For this reason I d suggest either importing the module and using it or importing specific names from the module   For example  your code would look like this with explicit imports   import socket from socket import AF INET  SOCK DGRAM  def main        client socket   socket socket AF INET  SOCK DGRAM      client socket settimeout 1      server host    localhost      server port   1234     while True           client socket sendto  Message    server host  server port           try              reply  server address info   client socket recvfrom 1024              print reply         except socket timeout               more code   Just a tiny bit more typing but everything s explicit and it s pretty obvious to the reader where everything comes from

User · Answer

Here is a solution I use in one of my project   network utils telnet  import socket from timeit import default timer as timer  def telnet hostname  port 23  timeout 1       start   timer       connection   socket socket       connection settimeout timeout      try          connection connect  hostname  port           end   timer           delta   end - start     except  socket timeout  socket gaierror  as error          logger debug  telnet error     error          delta   None     finally          connection close        return           hostname  delta         Tests  def test telnet is null when host unreachable self       hostname    unreachable       response   network utils telnet hostname       self assertDictEqual response    unreachable   None    def test telnet give time when reachable self       hostname    127 0 0 1       response   network utils telnet hostname  port 22       self assertGreater response hostname   0

User · Answer

I had enough success just catchig socket timeout and socket error  although socket error can be raised for lots of reasons  Be careful   import socket import logging  hostname  google com  port 443  try      sock   socket create connection  hostname  port   timeout 3   except socket timeout as err      logging error err   except socket error as err      logging error err

[python] Handling a timeout error in python sockets

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