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

From: Hiroshi Inoue <inoue(at)tpf(dot)co(dot)jp>
To: Barry Nicholson <b(dot)nicholson(at)niceng(dot)com>
Cc: pgsql-odbc(at)postgresql(dot)org
Subject: Re: FD_SETSIZE with large #s of files/ports in use
Date: 2010-05-19 03:36:34
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-odbc
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().

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

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