[libmicrohttpd] Re : Re: Re : Re: Re : Re: External select mode limited to 1024 FDs

[louisbenoit]

Hi Christian,

Looking at the 0.9.38 source code, I am getting confused.
Setting MHD_USE_THREAD_PER_CONNECTION eventually results in creating two threads:
    create_thread (&daemon->pid, daemon, &MHD_select_thread, daemon)
    create_thread (&connection->pid, daemon, &MHD_handle_connection, connection)
Entry points MHD_select_thread eventually calls select() on the listening socket.
Entry points MHD_handle_connection eventually calls select() on the connection socket.

Louis

Le 16/03/15, Christian Grothoff  <address@hidden> a écrit :

On 03/16/2015 05:09 PM, address@hidden wrote:
> Le 11/03/15, *Christian Grothoff * <address@hidden> a écrit :
>> On 03/11/2015 12:58 PM, address@hidden wrote:
>>> Hi Christian,
>>>
>>> I wanted to use external threads because my system has the following constraints:
>>> 1) One connection per thread: the response to the client is time critical and I cannot afford that a connection delays another one.
>>
>> Then you should use the one-thread-per-connection mode, that is exactly
>> what you want.  MHD will use a thread for each connection, which matches
>> your requirements.  This method also has no limits on open FDs as MHD
>> doesn't use select() but blocking read/write operations instead.
>
> Are you refering to MHD_USE_THREAD_PER_CONNECTION?

Yes.

> Or using
> MHD_OPTION_CONNECTION_LIMIT

No, that option has nothing to do with the threading modes.

> set to MHD_OPTION_THREAD_POOL_SIZE?

No, a thread pool is again different, as there you use one thread to
handle multiple connections, which may give you the delays you found so
problematic.

> In both cases shouldn't I use MHD_USE_POLL in order not to use select ()?

MHD_USE_POLL has no impact on MHD_USE_THREAD_PER_CONNECTION, as in that
case neither select() nor poll() are used anyway.

Happy hacking!

Christian