Perrin Harkins writes:
> On Tue, 5 Sep 2000, Michael Peppler wrote:
> > I've come across a technique that allows modperl processes to share a
> > pool of database handles. It's not something that I have seen
> > documented, so I figured I'd throw it out here.
> >
> > The idea is to create a pool of connections during the main
> > apache/modperl startup. Because these connections end up in the code
> > segment for the child processes they are completely shareable. You
> > populate a hash in a BEGIN block with x connections, and then provide
> > some calls to grab the first available one (I use IPC::Semaphore to
> > coordinate access to each connection).
>
> People have suggested this before on the mod_perl list and the objection
> raised was that this will fail for the same reason it fails to open a
> filehandle in the parent process and then use it from all the children.
> Basically, it becomes unshared at some point and even if they don't do
> things simultaneously one process will leave the socket in a state that
> the other doesn't expect and cause problems. You can cause pages to
> become unshared in perl just by reading a variable, so it's almost certain
> to happen sooner or later.
Yes, that's what I figured too. But in my tests, involving thousands
of database calls, I haven't seen any problems (yet).
> Can you try this some more and maybe throw some artificial loads against
> it to look for possible problems? It would be cool if this worked, but
> I'm very skeptical until I see it handle higher concurrency without any
> problems.
I will *definitely* throw as much load as I can in a test/stress
environment before I make use of this in a production environment.
I'll let y'all know how this goes...
Michael
--
Michael Peppler -||- Data Migrations Inc.
[EMAIL PROTECTED] -||- http://www.mbay.net/~mpeppler
Int. Sybase User Group -||- http://www.isug.com
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