Re: slapd size and file descriptors

[Howard Chu <hyc@symas.com>]

Quanah Gibson-Mount wrote:
> After some users reported that slapd had changed size enormously between
> two zimbra releases, I spent some time tracking down why.  Apparently, at
> least on linux, the startup size of slapd is directly related to the number
> of file descriptors it can access.
>
> For example, with 1024 file descriptors, slapd was 18MB resident and around
> 100MB virtual in size.  With some 550,000 file descriptors, slapd was
> 500MB+ virtual and 327MB resident.  This seems a bit odd.  Is this simply a
> "feature" of epoll() (I'm on a Linux 2.6 kernel)?

No, this is not OS dependent at all. slapd allocates its own Connection array 
based on the number of available descriptors. There's nothing unusual going on 
here, though 500K+ descriptors seems a bit excessive. Unless you have a server 
listening on multiple network interfaces, the most connections you're likely 
to get is 32768 or shy of 65536, depending on OS. You should really think 
about what you're trying to accomplish and what the realistic constraints 
actually are.
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP     http://www.openldap.org/project/