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Re: [libmicrohttpd] Doubts regarding MHD_OPTION_CONNECTION_LIMIT default
Fermín Galán Márquez
Re: [libmicrohttpd] Doubts regarding MHD_OPTION_CONNECTION_LIMIT default and usage of 0
Sun, 27 Nov 2016 16:55:18 +0100
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Thank you very much for so complete answer.
Only one minor doubt remains...
>> In addition, has 0 (as valid unsigned int) a meaning for this option? Or
>> just it mus not be used? Not sure about this looking the
>Currently value zero doesn't have any special meaning.
>You can start MHD with zero limit of number of accepted connection, if
I understand that doing so will end in MHD not accepting any connection.
Is my understanding correct, please?
El 26/11/2016 a las 12:05, Evgeny Grin escribió:
On 24.11.2016 22:20, Fermín Galán Márquez wrote:
From MHD documentation
the description of MHD_OPTION_CONNECTION_LIMIT is as follows:
//"Maximum number of concurrent connections to accept (followed by an
unsigned int). The default is FD_SETSIZE - 4 (the maximum number of file
descriptors supported by select minus four for stdin, stdout, stderr and
the server socket). In other words, the default is as large as possible."/
I wonder to which number refers that FD_SETSIZE in the documentation. I
1. To the FD_SETSIZE at system library, which happens to be 1024, at
least in my system looking to
/usr/include/x86_64-linux-gnu/bits/typesizes.h. I understand that in
other system it could be different number from different system
library .h, but always static and independent of the operating
FD_SETSIZE is number defined as FD_SETSIZE in system headers.
On GNU/Linux systems, it's 1024 in most cases.
However, on many systems (W32, FreeBSD, Solaris, Darwin) it's not
completely static and could be defined to any particular value before
including system headers.
MHD uses value of FD_SETSIZE as it was defined during MHD compilation.
If your application redefine FD_SETSIZE, need "external" polling mode
MHD mode and need to get fd_sets from MHD, just define FD_SETSIZE before
including "microhttpd.h" and MHD_get_fdset() macro will automatically
use your value of FD_SETSIZE.
2. To the actual file descriptors limit used by the operating system,
e.g. the one that can be changed with ulimit. In this case, the
setting is dynamic and I understand that the "maximum number of file
descriptor" is taken at process (using MHD) starting time.
Changing any system limits will not change sizes of 'fd_set' which
depends of value of FD_SETSIZE defined during compilation.
Which is the right one?
Value of FD_SETSIZE in system headers during MHD compilation as it
determines size of "fd_set" used by MHD compiled code.
In addition, has 0 (as valid unsigned int) a meaning for this option? Or
just it mus not be used? Not sure about this looking the documentation...
Currently value zero doesn't have any special meaning.
You can start MHD with zero limit of number of accepted connection, if