Bug#330105: libc6-dev: __FD_SETSIZE equals to 1024 is too small
Hello,
if you raise FD_SETSIZE in /usr/include/bits/typesizes.h and then
compile a software which uses select(), this software will be able to
handle more than 1024 FDs. Recompiling glibc, the kernel or whatever
else is not necessary.
I tested this solution with UnrealIRCd and 8000 clients. Unfortunately,
I don't know enough about the way glibc works, but I found this in the
FAQ of the debian libc6 source package:
--------
2.25. I need lots of open files. What do I have to do?
{AJ} This is at first a kernel issue. The kernel defines limits with
OPEN_MAX the number of simultaneous open files and with FD_SETSIZE the
number of used file descriptors. You need to change these values in
your
kernel and recompile the kernel so that the kernel allows more open
files. You don't necessarily need to recompile the GNU C library since
the
only place where OPEN_MAX and FD_SETSIZE is really needed in the library
itself is the size of fd_set which is used by select.
The GNU C library is now select free. This means it internally has no
limits imposed by the `fd_set' type. Instead all places where the
functionality is needed the `poll' function is used.
If you increase the number of file descriptors in the kernel you don't
need
to recompile the C library.
--------
Would it be possible to add a #ifndef FD_SETSIZE around the definition
in /usr/include/bits/typesizes.h in order to give other software the
possibility to change the value without modifying the system headers?
Regards,
Christoph
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