On 21/12/14 16:54, Petr Baudis wrote:
Hi!
I tried to use Apache Fuseki for my QA system, loaded up with part of
DBpedia and set up according to:
https://github.com/brmson/yodaqa/blob/master/data/dbpedia/README.md
It works beautifully, but the system puts Fuseki under a pretty heavy
load, with several tens of SPARQL queries per second at times, often in
parallel. And after about an hour on average, Fuseki just hangs up,
still accepting new queries but never generating a result.
I suspect it might be some kind of deadlock, but I would need some
advice on how to debug it best or what kind of data you would need.
(If you think for this usecase, a different kind of server would be
better, I'll be happy to hear suggestions too. :-) I was using Virtuoso
so far, but with abysmal experience (self-corrupting database, hangs of
different kind), and couldn't get 4store to work; I imported the data
but never made it to return any data in finite time with SPARQL queries
that work with Virtuoso and Fuseki.)
Thanks,
Petr Baudis
Hi Petr,
What is the setup in terms of hardware (RAM size, number of CPUs etc
etc), operating system and versions? The details do matter here.
This may be JENA-801 [1].
If so, there is a suggested fix but the code contribution hasn't arrived
yet.
I believe the reporter of JENA-801 (Bala Kolla) used something related
to this to replace CacheLRU:
https://github.com/afs/AFS-Dev/blob/master/src%2Fmain%2Fjava%2Fprojects%2Fcache%2FCacheGuava.java
though if we are going to use Guave Cache (which is highly likely) then
there is a even better way to use in the presence of updates. That's
why I'd like to see what has been done to know if the update chnages
were also tried out. If for your usage, it is just query load, I can
build a special for you to try out (or you can : replace the body of
CacheLRU with CacheGuava body, add dependency to ARQ and build with maven).
Andy
[1]
https://issues.apache.org/jira/browse/JENA-801
