Re: deferring operation: pending operations

[Howard Chu <hyc@symas.com>]

Ben Beuchler wrote:
> On 4/7/07, Howard Chu <hyc@symas.com> wrote:
> > Ben Beuchler wrote:
> > > Apr  5 11:32:52 swizzle slapd[1626]: connection_input: conn=6232680
> > > deferring operation: pending operations
> > >
> > > What does "deferring operation: pending operations" actually indicate?
> > It means that an operation that was just received on that connection has
> > been deferred, because there are other operations ahead of it that are
> > still pending. I.e., there's a bunch of operations on that connection
> > waiting to execute, and the newcomer is last in line.
>
> Hmmm.  That particular connection rarely makes more than a couple
> search or bind requests per second.  Well within what OpenLDAP should
> be able to handle on a nice, fast server like this.  Is there a class
> of mistakes that the client could be making to cause operations to
> queue up like this?

The only time I've seen this occur on a frequent basis is with poorly 
written clients like Sendmail, which sends off a stream of a hundred or 
so search requests on a connection before it checks for any replies. The 
problem there is that the search replies build up in the network and 
socket buffers and once the socket buffer gets full we can't send 
anything else. At that point we stop executing operations on the 
connection; we just wait for the client to drain it.

--
  -- 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/