Re: corba config caching

[Elliot Lee <sopwith redhat com>]

On Wed, 21 Apr 1999, Dave wrote:

>   I haven't done any Gnome programming (yet) so dont flame me if I'm
> wrong, but in my experience, it seems that sometimes Gnome/E suffer from
> slight latency based on the fact that all config files are in various
> ascii files.  So when many of these need to be read at once for something
> such as starting panel, it must go through and parse them all one by one.
>   My idea is to have some sort of caching config daemon(?) that would
> communicate possibly using ORBit.  It could keep all this config
> information in a binary cache file (similar to sendmail) and would
> automatically update said cache when the modify times on the files
> changed.  It wouldnt be too hard to implement and unless Im mistaken,
> would add noticable performace benefits.

The idea of using a CORBA service to arbitrate access to the config files
has been floating around for a while. You may be correct that it would
speed up access to config items, but I'm not sure whether you've taken
into account the complexity and overhead that CORBA brings.

Having to talk to another process by any IPC means is expensive, and CORBA
adds overhead on top of the raw communications & context switch costs.
There's also the noticeably. increased memory usage compared to the
present approach.

There is also the issue of complexity. Introducing a dependency on an
external config server means that GNOME apps would potentially crash if
the config server crashed. How would you solve this problem? The GNOME
CORBA framework uses gnome_config to retrieve information about available
object implementations. How would this apparent dependency loop be solved?

The present solution definitely has its problems. It has traveled the
pendulum between race conditions and suboptimal performance several times,
and is not 100% "nice".

Further investigation would help shed some light on exactly how the
performance would compare. I'm not saying either way is the right
solution, just that there's no conclusive information in either direction.

-- Elliot
"We're sorry, we didn't know it was supposed to be invisible."
	- Sign carried outside US embassy.