Thanks for the reply Thomas

I forgot to mention that the 1000+ attachments we are expecting is over about 60 databases, where the maximum attachments to a single database is about 50. How will this affect the contention on the lock table?

--- In firebird-support@yahoogroups.com, Thomas Steinmaurer <ts@...> wrote:
>
> > What is the current maximum number of connections firebird(2.1/2.5) can
> > handle on a wondows 2008 r2 server. Is it still the 1024 limit set by the
> > OS or has this changed?
>
> Just connecting with 2.5.2 SC 64-bit snapshot on Win 7 Prof. with 12GB
> RAM and 75 page buffers without doing anything in context of these
> connections:
>
> SQL> select count(*) from mon$attachments;
>
> COUNT
> ============
> 1201
>
> Perhaps higher possible. What you can see is that the number of threads
> of the SC process stays at 1029. Doing some work then (with a SMP-test
> utility I once wrote for a presentation; see below), you will get VERY
> high (*g*) contention on the lock table:
>
> Hash slots: 1009, Hash lengths (min/avg/max): 57/ 83/ 102
>
> with the default hash slot value of 1009. Quit that test.
>
> The SMP-testing utility basically allows to simulate a configurable
> number of client attachments via one thread per client attachment. It does:
>
> - Insert <n> records per attachment into a GTT via one simple stored
> procedure call
> - Each attachment will fetch the inserted records to the client
>
> Another workload with 1201 client attachments (2 SMP-test utility
> instances running), processing (inserting into GTT and fetching) 5000
> records each. This time with a higher hash slots value.
>
> - 5000 records per attachment into a global temporary table via one
> simple stored procedure
> - Each attachment will fetch the inserted records to the client
>
> My AMD hexa-core workstation was busy, but the test was finished in ~50
> seconds. Took a lock print during the fetching phase.
>
> Hash slots: 10133, Hash lengths (min/avg/max): 0/ 4/ 15
>
>
> > The question arises because we would like to consolidate two servers, and
> > one of them already has about 800-900 attachements(A program written en
> > delphi using a connected model). The other server has about 300
> > attachements. serving websites and webservices(using connection pooling)
>
> The question is if you really need that number of physical connections
> from your Delphi application and what you are doing in context of your
> connections. If one instance doesn't handle the load, you still can run
> a second on the same server, if you have enough resources available. But
> these days, with low hardware prices, virtualization etc. ...
>
>
> --
> With regards,
> Thomas Steinmaurer (^TS^)
> Firebird Technology Evangelist
>
> http://www.upscene.com/
> http://www.firebirdsql.org/en/firebird-foundation/
>