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Subject: RE: sysconf(_SC_OPEN_MAX) limit
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Date: Fri, 8 Jun 2001 11:33:38 +1000
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Thread-Topic: sysconf(_SC_OPEN_MAX) limit
Thread-Index: AcDvuqqIopmAOJO9TAe5e/q9XuryZgAAA3Iw
From: "Robert Collins" <robert DOT collins AT itdomain DOT com DOT au>
To: <cygwin AT cygwin DOT com>
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> -----Original Message-----
> From: Christopher Faylor [mailto:cgf AT redhat DOT com]
> Sent: Friday, June 08, 2001 11:40 AM
> To: cygwin AT cygwin DOT com
> Subject: Re: sysconf(_SC_OPEN_MAX) limit
> 
> 
> I checked into this.  sysconf() is returning the current size of the
> fd table.  The fd table starts at 32 and is extended as needed.
> 
> I don't know what sysconf should return, actually.  The number of
> possible fds is obviously not infinite but it is pretty 
> large.  Perhaps
> we should just return an arbitrary large number like 4096 or 
> something.

I just had that discussion off-list...

The maximum number of handles per process is 65,536, shared across
mutex's, open files, pipes, spinlocks etc. Note that cygwin may uses
more than 1 handles per fd for some fd's (ie two unidirectional pipes..)

Programs like squid and other servers will want a large number of fd's
avilable, so I suggest 16K as  a reasonable compromise.

Rob

> 
> cgf
> 
> On Thu, Jun 07, 2001 at 08:06:30PM -0400, Suhaib Siddiqi wrote:
> >Thanks Rob,
> >For me 255 was enough ;-)
> >
> >Suhaib
> >
> >> -----Original Message-----
> >> From: Robert Collins [mailto:robert DOT collins AT itdomain DOT com DOT au]
> >> Sent: Thursday, June 07, 2001 8:04 PM
> >> To: Suhaib Siddiqi; cygwin AT cygwin DOT com
> >> Subject: Re: sysconf(_SC_OPEN_MAX) limit
> >> 
> >> I think it's newlib that provides sysconf....
> >> 
> >> I'll see if I have time this weekend to dig into where the 
> 32 is coming
> >> from. 8192 /16384 sound good for the value returned?
> >> 
> >> Rob
> >> 
> >> ----- Original Message -----
> >> From: "Suhaib Siddiqi" <ssiddiqi AT inspirepharm DOT com>
> >> To: <cygwin AT cygwin DOT com>
> >> Sent: Friday, June 08, 2001 9:56 AM
> >> Subject: sysconf(_SC_OPEN_MAX) limit
> >> 
> >> 
> >> >
> >> > According to private communication with Chris, Cygwin 
> has no fd limit.
> >> >
> >> > However, we have a sysconf(_SC_OPEN_MAX) issue for 
> Cygwin/XFree86:
> >> >
> >> > why sysconf(_SC_OPEN_MAX) only returns 32 then. XFree86 
> returns errors
> >> once
> >> > max limit is hit.  One way to over come this is to hack the
> >> connections.c in
> >> > Xfree86, However, shouldn't
> >> > this be bumped up in the Cygwin rather than making 
> changes in source
> >> code
> >> > outside of
> >> > it. Maybe other people will come across the same problem in other
> >> > applications.
> >> >
> >> >
> >> > --
> >> > Want to unsubscribe from this list?
> >> > Check out: http://cygwin.com/ml/#unsubscribe-simple
> >> >
> >> >
> >
> >--
> >Want to unsubscribe from this list?
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> 
> -- 
> cgf AT cygnus DOT com                        Red Hat, Inc.
> http://sources.redhat.com/            http://www.redhat.com/
> 
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> 

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