Hi,

> Sometimes, it happens that one of the Firebird process takes 100% of one
> CPU core and after that Firebird doesn�t accept any other connection and
> we must kill the FB process manually. We have tested it with FB 1.5, CS,
> SS and there occurs this problem too. The interval between these events is
> shorter when the database goes bigger (at this time is about 600MB). Our
> web site has about 200 hit/sec in its peak and this generates about 2000
> simple db queries per sec.
> Does anybody know what can cause this situation?

Most probably it's a sweep kicking in. What are your sweep settings? Can
our offload sweep to a specific time of the day/week?
Have you checked for indexes with many duplicates? Firebird 2.0 can
handle them much better, should be worth a try too.
Have you checked for long-running transactions? Show us the header page
as per "gstat -h".
I don't think this is a PHP problem, so you should take this over to
firebird-support imo.

regards,
Michael