Re: Lock is no longer valid / deferring operation

[Toby Blake <toby@inf.ed.ac.uk>]

Hi again Gavin,

<most stuff snipped>

> > As for what services they provide, general desktop services, but also
> > could be running long-running or intensive jobs.  Many of the machines
> > are also in a condor pool and this does seem to cause more problems.
> >
> > Do you know if slapd gets unhappy if other processes use up lots of
> > memory?  This is my current line of investigation - I'll try to make
> > it unhappy by using increasing amounts of memory.
>
> Yes.
>
> > I suppose what I'm trying to determine is - is it the client activity
> > that's causing problems (i.e. a misbehaving client or similar) or is
> > it slapd itself getting unhappy for other reasons (possibly due to
> > resources being used by other programs)?  Or a combination of both?
>
> Probably both. If a client keeps sending lots of bind/search requests at
> once, slapd will queue/defer them.

Excellent, this does look to be the case.  I've just run a bit of a
test by eating up all memory and swap and seeing if I could upset
slapd - it seemed OK for a while, then a full search of the directory
triggered off a "Lock is no longer valid" and it's now distinctly
unhappy.  So, a client that not only eats memory, but also uses up
other resources, to the detriment of slapd, can only produce
problems.

I suppose the way forward is to migrate away from running local slapd
everywhere, perhaps to a proxy-caching type of solution, but this is
going to require some proper planning and investigation.

Again, thanks for your help.

Cheers
Toby