Re: [libmicrohttpd] MHD in "worker processes" mode

[Christian Grothoff]

On 06/10/2016 09:20 PM, Junker, Gregory wrote:
> On Fri, 2016-06-10 at 13:37 +0200, Christian Grothoff wrote:
>> On 06/10/2016 02:04 AM, silvioprog wrote:
>>>
>>> Hello,
>>>
>>> Please take a look at this question and the first answer:
>>>
>>> http://askubuntu.com/questions/399431/how-many-nginx-processes-shou
>>> ld-there-be
>>>
>>> It raise a question: can I use the worker processes approach with
>>> MHD?
>>> If I understood, it need to up two or more process, but when I try
>>> that:
>>> "Failed to bind to port 8080: Address already in use".
>> You can have a parent process do the binding and then share the
>> listen
>> socket with child processes. Or, you can on most OSes set the binding
>> policy to allow multiple processes to listen to the same socket.
> 
> Interesting, I did not know that was an option. What are the rules
> about which process gets released from a select() or poll in that
> case? 

It's a (benign) race. Statistically speaking, the process that is less
busy ;-).  MHD exploits the same race when multiple threads are in a
thread pool racing to accept on the listen selector in-process.

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