Subject Re: [firebird-support] Classic vs Superserver
Author Tim Ward
On 29/08/2013 18:31, Alexandre Benson Smith wrote:
> Em 29/8/2013 12:17, Tim Ward escreveu:
> > But I thought Superserver used threads? And threads can run on
> > separate CPUs? (Processes are an address space thing, not a CPU thing.)
> There are threads, but in fact they are "serialized", perhaps it's just
> an over simplification, I don't know FB internals, but the threads does
> not run in parallel (FB 3.0 will fix that). If you have a multi core
> server (wich is an obvious thing theses days) you should prefer Classic
> Server, the only case where I think SuperServer will be a choice is when
> you have just one connection per database.
So Superserver is in effect single threaded and will use only a fraction
of the power of even one of today's modest desktop PCs let alone a
server - thanks, this wasn't obvious to me from the documentation.
> Perhaps you have automatic sweep disabled (check with gstat -h), if you
> have sweep disabled the garbage will acumulate, so when a query need to
> "scan" the table it will pay the cost to clean it up. I am not saying to
> use automatic sweep, since it could trigger in the middle of the day
> generating an "unknown" slowdown... What I suggest is that you keep
> automatic sweep disabled and run a manual sweep (gfix -sweep) during off
> peak hours.
Automatic sweep is indeed disabled, but "manual sweep during off peak
hours" isn't practical. The system can need to run flat out for a couple
of days at a time, and the problem arises after only a few hours.

Tim Ward

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