Re: [Exist-open] XQuery performance

[Sebastian B. <sb...@jb...>]

On Tuesday 30 November 2004 10:48, Teemu Hiltunen wrote:
> The problem is that when there comes more than one request at the
> same time (or in time when the first query is still processing) ALL
> queries slow down dramatically. Like, if there is only one thread
> (request) the query time is the mentioned 2s, but when there are
> three concurrent threads (requests) the query times for each query
> are 4.5 seconds and with ten concurrent threads (requests) the
> query times for each query are 17 seconds!!! What is the problem?

I am not quite sure I understand the problem: If your system needs 2s 
per query for one query at a time, the tripling the system load 
(running three queries at the same time) should appx. triple the time 
per query (so I would expect each query to take up to 6 seconds). 

Increasing the load tenfold increases the time per query by the same 
factor of 10. The times you observe seem to be below those estimates, 
thus there are some synergies in concurrency.

I think that a time per query that remains at 2 seconds regardless of 
amount of concurrent queries would be quite strange.

Sebastian

-- 
Sebastian Bossung
Software Systems Group (4-02)
Hamburg University of Technology
Harburger Schlossstrasse 20, 21071 Hamburg, Germany
http://www.sts.tu-harburg.de/~se.bossung