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Re: Strange Socket problem

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On 3/1/2012 2:15 PM, Martin Gregorie wrote:
> On Thu, 01 Mar 2012 11:49:30 -0800, Knute Johnson wrote:
>
>> I'm having a problem in some production code that I can't figure out.
>> I'll post the complete actual code below.  This code is running in three
>> places and has the same problem in two of them at the same time.  The
>> other I'm not sure, it may be that the personnel operating it are
>> restarting the program and so don't complain.  This piece of code is a
>> simple client that connects via a Socket to a server.  The server
>> supplies some data and the client reads that data and files it away.  It
>> is supposed to restart itself if there is a connection failure or fault
>> for whatever reason.  The problem is that at some random point in time
>> the Socket disconnects, the code logs the disconnect but never restarts.
>>    It does print the "SportsWinClient Disconnected" message but never
>> executes the "fireconnectionEvent()" method after creating a new Socket.
>>    It doesn't print any Exception message.  I'm not sure how it gets out
>> of the try block without printing the "End of Stream" message or an
>> exception message.
>>
>> The crazy part is that all night long when there is no activity from the
>> server it times out and restarts with no problems.
>>
> I notice that InetAddress.getByName() can throw UnknownHostException (and
> this exception isn't explicitly handled. Is it possible that this call
> can time out when the network is busy?

That's possible I guess but I would think it would still throw an 
UnknownHostException.  Also, since I pass it a string with the IP 
address specified with digits, it doesn't have to do any DNS lookup.

> However, as UnknownHostException is a subclass of IOException I don't see
> how it avoids being caught, unless a timeout causes a null to be
> returned: the description of getByName() isn't at all clear about when a
> null is returned instead of throwing an exception. Pulling this out of
> the new Socket() statement so it can be tested for a null return would at
> least show whether this is happening.
>
> Also, I don't see why you're using InetAddress to pass what is apparently
> a remote address to the Socket constructor as localAddress, or why you're
> using port zero  as the local port.

The computer has two NICs.  The LOCAL_IP is the address of the NIC that 
I want to use to connect to the server.  Having to use InetAddress is a 
limitation of the Socket constructor.  Port 0 is the ephemeral port.  It 
allows the socket implementation to select any available port for the 
client end.  I'm not sure how InetAddress.getByName() can return a null.

-- 

Knute Johnson

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Thread

Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-01 11:49 -0800
  Re: Strange Socket problem Steven Simpson <ss@domain.invalid> - 2012-03-01 20:59 +0000
    Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-01 13:30 -0800
      Re: Strange Socket problem Steven Simpson <ss@domain.invalid> - 2012-03-01 22:54 +0000
        Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-01 16:32 -0800
          Re: Strange Socket problem Steven Simpson <ss@domain.invalid> - 2012-03-03 09:08 +0000
            Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 17:48 -0800
  Re: Strange Socket problem markspace <-@.> - 2012-03-01 14:08 -0800
    Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-01 16:48 -0800
      Re: Strange Socket problem markspace <-@.> - 2012-03-02 08:33 -0800
        Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-02 15:29 -0800
          Re: Strange Socket problem markspace <-@.> - 2012-03-03 09:33 -0800
            Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 17:55 -0800
              Re: Strange Socket problem markspace <-@.> - 2012-03-03 20:06 -0800
                Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 21:02 -0800
                Re: Strange Socket problem "John B. Matthews" <nospam@nospam.invalid> - 2012-03-05 00:00 -0500
                Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-05 09:44 -0800
  Re: Strange Socket problem Martin Gregorie <martin@address-in-sig.invalid> - 2012-03-01 22:15 +0000
    Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-01 16:43 -0800
      Re: Strange Socket problem Martin Gregorie <martin@address-in-sig.invalid> - 2012-03-03 02:01 +0000
  Reiteration: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-01 16:51 -0800
    Re: Reiteration: Strange Socket problem Martin Gregorie <martin@address-in-sig.invalid> - 2012-03-03 02:02 +0000
  Re: Strange Socket problem x <x@x.x> - 2012-03-02 21:18 +0100
    Re: Strange Socket problem Lew <noone@lewscanon.com> - 2012-03-02 15:06 -0800
      Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-02 15:38 -0800
        Re: Strange Socket problem Lew <noone@lewscanon.com> - 2012-03-02 16:00 -0800
          Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-02 17:18 -0800
            Re: Strange Socket problem Martin Gregorie <martin@address-in-sig.invalid> - 2012-03-03 02:13 +0000
              Re: Strange Socket problem Steven Simpson <ss@domain.invalid> - 2012-03-03 08:41 +0000
                Re: Strange Socket problem Martin Gregorie <martin@address-in-sig.invalid> - 2012-03-03 18:26 +0000
        Re: Strange Socket problem x <x@x.x> - 2012-03-03 11:32 +0100
          Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 17:59 -0800
          Re: Strange Socket problem Lew <noone@lewscanon.com> - 2012-03-03 23:21 -0800
      Re: Strange Socket problem x <x@x.x> - 2012-03-03 10:59 +0100
        Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 18:08 -0800
    Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-02 15:33 -0800
  Re: Strange Socket problem Paka Small <paka-en@tumia.org> - 2012-03-03 03:32 -0800
    Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 18:00 -0800
  Re: Strange Socket problem x <x@x.x> - 2012-03-03 12:45 +0100
    Re: Strange Socket problem Knute Johnson <nospam@knutejohnson.com> - 2012-03-03 18:02 -0800

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