serverid(s)_exist, critical path work.

Volker Lendecke Volker.Lendecke at SerNet.DE
Thu Feb 7 06:03:01 MST 2013

On Thu, Feb 07, 2013 at 07:55:42AM -0500, Ira Cooper wrote:
> On Thu, Feb 7, 2013 at 7:07 AM, Volker Lendecke
> <Volker.Lendecke at>wrote:
> > On Thu, Feb 07, 2013 at 06:13:31AM -0500, Ira Cooper wrote:
> > > >From Andrew Bartlett's review on IRC:
> > >
> > > Why remove TDB, isn't that a step backwards?
> >
> > To be honest, right now I'm in the mood to see this actually
> > a step forward. fcntl sucks so badly that I would call it
> > unusable. I am really ripping out my hair right now to
> > replace it with something sane, although that turns out to
> > be much more difficult than initially expected :-(
> The gap TDB fills must be filled by "X".  The general comment is sound, the
> specific instance... well... I wrote the patch.
> Also note, I view what I'm doing as an "index" here, all the real data is
> on the side, this is to speed up one very hot function.  The general
> function of serverid.tdb should not be impacted.

True. I just have my little tdb/fcntl-blues. I had thought
that unix domain datagram sockets are really scalable, but
that also seems not to be the case. My tests on FreeBSD and
modern Linux also gave problems.

So it seems that the only really scalable IPC mechanism
(scalable in terms of many, many thousand instances of
*something*) seems to be epoll and its cousins on other
OSes. I wonder if we can build something fast and robust
upon those.

Commenting on your patch: In theory, the load on
serverid.tdb should be a lot less in master, as we do not
look up every process anymore when reading a share mode
record. We only do it when we have a conflict. I would be
curious if this patch has a big effect when tested with


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