Re: FD_SETSIZE with large #s of files/ports in use

Hiroshi Inoue wrote:
> Hi,
>
> Could you please try the attached patch?

Oops it doesn't seem to work.
Another way is to use poll() instead of select().

regards,
Hiroshi Inoue

> regards,
> Hiroshi Inoue
>
> Barry Nicholson wrote:
>> An interesting issue came up the other day.  We are working with an
>> application that opens a considerable number of files and tcp/udp
>> ports (>3000).   Unfortunately, that means that the odbc driver fails
>> sometimes due to a corrupted stack.  We eventually figured out what
>> was causing the corrupted stack.
>> The SOCK_wait_for_ready(SocketClass *sock, BOOL output, int
>> retry_count) function inside socket.c calls select.  Unfortunately,
>> the socket file descriptor number can be quite large at this time.
>> That means that the fd_set fds variable can misused.   The fd_set
>> variable type only allows 1024 file descriptors to be used by the
>> calling program on many Linux versions.   This can be changed by
>> setting FD_SETSIZE or __FD_SETSIZE to a larger number.   We have ran
>> tests where we were able to change the __FD_SETSIZE value in
>> /usr/src/...linuxversion../linux/include/linux/posix_types.h.   The
>> fix worked well.
>>
>> Unfortunately, this isn't a good solution because a software update to
>> another linux version will invalidate our fix.   We've tried various
>> mechanisms to set FD_SETSIZE or __FD_SETSIZE in socket.c but with no
>> luck.   Has anyone else had this problem and came up with a good
>> fix?   Or is there a better solution?
>>
>> Barry Nicholson
>> Niceng.com