users@grizzly.java.net

Re: detect network disconnected?

From: ichinco <ichinco_at_gmail.com>
Date: Mon, 4 Jan 2010 11:02:31 -0800 (PST)

I'm not sure-- how would I be able to tell?

I know that tcp_no_delay=on in our system.


Igor Minar wrote:
>
> just a though - it is possible that socket buffers of the underlying
> OS and TCP_NO_DELAY=off settings are getting in the way of reliably
> detecting network disconnect.
>
> /i
>
> On Jan 4, 2010, at 10:50 AM, ichinco wrote:
>
>>
>> Hi!
>>
>> Back from break now!
>>
>>
>> Oleksiy Stashok wrote:
>>>
>>> Agree. From what I know, if connection was closed read() operation
>>> will return either -1 or throw IOException (depending on OS and JDK).
>>> Unfortunately it's also true, that write operation may succeed on
>>> connection, which was closed by peer.
>>>
>>> Also agree, that "Heart beat" mechanism could be a good solution.
>>>
>>
>> I tried this as well, with no success. (read returns 0 and does not
>> throw
>> and exception, even when the network cable is pulled.)
>>
>> I can think of two things:
>>
>> First, we're using non-blocking I/O. Is it possible that there is an
>> error,
>> but that we aren't seeing it?
>>
>> Second, is it possible that it will only error after some timeout?
>> If so,
>> where do I set the timeout? (I've tried
>> TCPSelectorHandler.socketTimeout,
>> but can't seem to figure out under what circumstances it would
>> actually
>> timeout or what that would look like on the server side.)
>>
>> I'm not an expert on sockets by any means, but it seems like sockets
>> that
>> are "normally" closed send and EOF, get handled by the
>> ConnectionClosedHandler, and return -1 if you try to read from them.
>> In this
>> case, we're not getting the EOF, and we're not getting any of the
>> other
>> stuff either. Without an EOF, then, we're screwed?
>>
>> Any ideas?
>>
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>>
>>
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