Does Fuseki have direct code dependency on Jetty? Or would it be possible
to try switching to a different servlet container such as Tomcat?
JAX-RS, which I’ve advocated here multiple times, provides such a
higher-level abstraction above servlets that would enable easy switching.
On Fri, 25 Aug 2023 at 16.18, Dave Reynolds
wrote:
> On 25/08/2023 11:44, Andy Seaborne wrote:
> >
> >
> > On 03/07/2023 14:20, Dave Reynolds wrote:
> >> We have a very strange problem with recent fuseki versions when
> >> running (in docker containers) on small machines. Suspect a jetty
> >> issue but it's not clear.
> >
> > From the threads here, it does seem to be Jetty related.
>
> Yes.
>
> We've followed up on Rob's suggestions for tuning the jetty settings so
> we can use a stock fuseki. On 4.9.0 if we switch off direct buffer using
> in jetty altogether the problem does seem to go away. The performance
> hit we see is small and barely above noise.
>
> We currently have a soak test of leaving direct buffers on but limiting
> max and retained levels, that looks promising but too early to be sure.
>
> > I haven't managed to reproduce the situation on my machine in any sort
> > of predictable way where I can look at what's going on.
>
> Understood. While we can reproduce some effects in desktop test set ups
> the only real test has been to leave configurations running for days at
> a time in the real dev setting with all it's monitoring and
> instrumentation. Which makes testing any changes very painful, let alone
> deeper investigations.
>
> > For Jena5, there will be a switch to a Jetty to use uses jakarta.*
> > packages. That's no more than a rename of imports. The migration
> > EE8->EE9 is only repackaging. That's Jetty10->Jetty11.
> >
> > There is now Jetty12. It is a major re-architecture of Jetty including
> > it's network handling for better HTTP/2 and HTTP/3.
> >
> > If there has been some behaviour of Jetty involved in the memory growth,
> > it is quite unlikely to carried over to Jetty12.
> >
> > Jetty12 is not a simple switch of artifacts for Fuseki. APIs have
> > changed but it's a step that going to be needed sometime.
> >
> > If it does not turn out that Fuseki needs a major re-architecture, I
> > think that Jena5 should be based on Jetty12. So far, it looks doable.
>
> Sound promising. Agreed that jetty12 is enough of a new build it's
> unlikely to have the same behaviour.
>
> We've being testing some of our troublesome queries on 4.9.0 on java 11
> vs java 17 and see a 10-15% performance hit on java 17 (even after we
> take control of the GC by forcing both to use the old parallel GC
> instead of G1). No idea why, seems wrong! Makes us inclined to stick
> with java 11 and thus jena 4.x series as long as we can.
>
> Dave
>
>
