On 21/10/2022 13:42, [email protected] wrote:
Hello Christophe,
I am relatively new to Fuseki, so take my feedback with a grain of salt.
I recall reading that Fuseki accumulates updates in memory while readers are
active, and that only when there are no readers does it apply accumulated
updates. This means that if you have a multi-threaded application with frequent
reads and writes, you will likely gradually fill up memory until there’s a
pause in reading and there’s a chance to write out the accumulated updates. I
experienced this with an application I was running with 30 threads in parallel.
It filled up my workstation’s memory, and my workstation crashed. I reduced the
number of concurrent threads to 1, and the problem did not recur.
This is true but only for TDB1 and only if a sequence of overlapping
requests happens during and continues after a writer. (If it had enough
memory it gets quite pushy about letting the writer post-commit
finalization happen.)
This is only of the reasons for TDB2. It does not accumulate updates in
memory - in fact it writes changes back during the transaction.
Andy
You could try reducing the number of threads, or try pausing all readers—if
that’s possible—to give Fuseki a chance to write out accumulated updates.
All the best
Ted
Theodore Hills
Consultant | Research
Phone: +1 212 296-1833
[email protected]<mailto:[email protected]>
From: christophe heligon <[email protected]>
Sent: Thursday, October 20, 2022 7:30 AM
To: users <[email protected]>
Subject: Memory leak in fuseki? (attached file included)
Hi everyone,
I am using Apache Jena Fuseki 4.6.1 to host 2 datasets (rdf + rdf-star).
I have noticed an unexpected behaviour on my server as my RAM gets filled
little by little over time ( 100 Mo / few minutes can be several Go at the end)
when no queries are received by the server. When I submit a query using fuseki
GUI the RAM gets freed (at least partially) from what seemed to have
accumulated into it in between queries.
The java process is using that memory see attached file. Note that I use the
standard configuration provided by the server except for the max memory that I
set to 20 Go. The java process is largely exceeding this limit as it may reach
over 50 Go.
Is it a known issue of Fuseki? Java?
Is there a way to monitor that better than just record memory use?
Any fix published or hint on how to solve that?
Best regards,
Christophe
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Christophe Héligon
Institut de Génétique & Développement de Rennes
Equipe Ingénierie Inverse de la Division Cellulaire (CeDRE)
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