On 02/09/13 12:51, nadav hoze wrote:
hi,
We are doing stress tests to our service which it's underlying data layer
is jena TDB.
one of our tests is tor run heavy queries for long time (about 6 Hrs) and
afterwards run light queries. (we have clients which are in that mode).
What we witness is a huge performance degradation, light queries which
usually took around 0.1-0.2 sec after the heavy queries execution took more
than 3 seconds.
Not surprising - the heavy queries will have taken over the OS
cache.(assuming 64 bit - a similar effect occurs on 32 bit). The
light-after-heavy is effectively running cold.
Also the heavy query execution had a huge performance degradation after
only one minute:
each heavy query fetched around 35000 triplets and for the first minutes
it took between 10-40 seconds (which is OK), afterwards it peaked to
200-8000 seconds.
Same thing memory wise, after a minute it peaked from 200mg to 2.2g.
What I would like to know is if there could be memory leak in jena, or
whether jena objects are cached in some way and maybe we can release them.
Here are important details for answering:
*jena version: 2.6.4*
*tdb version: 0.8.9*
*arq: 2.8.7*
*we use a single model and no datasets.*
Also can an upgrade to jena latest stable version help us here ?
You should upgrade anyway. There are bug fixes. And a different license.
Help is much appreciated :)
All depends on what the heavy query touches in the database (the pattern
matching part), the size of the machine, whether anything else is
running on the machine, ...
There are many, many factors:
What size of the machine?
What OS?
Is it a VM?
How much data (in triples) is there in the DB?
Heap size?
The driver program is on What
the same machine as the database - does this matter?
...
Andy
Thanks,
Nadav
