Special exception for EMFILE / ENFILE when using sockets.

[Norman Maurer]

> Am 05.12.2016 um 18:48 schrieb David M. Lloyd <david.lloyd at redhat.com>:
> 
>> On 12/05/2016 06:29 AM, Norman Maurer wrote:
>> Hi all,
>> 
>> I wonder if it would be possible to add a new public exception time for the situation of an SocketChannel.accept(…) or SocketChannel.open(…)  (and the same for ServerSocket / Socket) failing because of too many open files.
>> The reason is because especially when acting as a server such an exception may be something you can easily recover from. At there is basically no way to detect if this was the cause of an IOException or not.
>> 
>> On unix / linux this are the errno values:
>> 
>> [EMFILE]           The per-process descriptor table is full.
>> [ENFILE]           The system file table is full.
>> 
>> For netty we would love to be able to know if this was the case of the problem and if so just stop accepting for a period of time to help the system to recover.
>> 
>> What others think about this ?
> 
> I like the idea, but maybe it should be a general IOException since this same error can happen on file open, selector creation (sometimes), pipe creation, etc.
> 
> -- 
> - DML

Sure that would work for me as well :)

Bye,
Norman