[undertow-dev] Loss of perfomance between 1.3.0.Beta9 and 1.3.18.Final
Stuart Douglas
sdouglas at redhat.com
Wed Mar 9 20:49:31 EST 2016
TLDR: Looks like there is a problem in XNIO accept handling, I have submitted a PR, after my PR it should be considerably faster than Beta9 (at least on my machine). This problem only affects non-persistent connections.
I have looked into this a bit more, I have done some testing on my linux machine (4 core CentOS).
Running the benchmark as described with the NO_REQUEST_TIMEOUT set to -1 I get:
Beta9: 23031
1.3.18.Final: 22578
However adding -k to the ab command to use persistent connections gives a different result:
Beta9: 169100
1.3.18.Final 173462
This implies that the issue is only with non persistent connections. Something that did change between Beta9 and 1.3.18.Final is XNIO connection handling, which has been changed to use a dedicated accept thread. Looking into this I have noticed a potential problem that is causing contention. I have submitted a fix at https://github.com/xnio/xnio/pull/94.
Something else to note is that ab was 100% maxed out on a CPU core when running these tests. In general ab is not a great load driver as it is single threaded.
The results get much more interesting if you modify the bench.sh slightly by adding an '&' to the end of the ab line and removing the 'sleep 5' call. This makes all 5 ab instances run at once, which is enough to max out the CPU on my machine (I also multiplied the number of requests by 5, the current number is a bit low).
Using this approach I get the following results (3.3.6.Final-SNAPSHOT includes the PR I linked above):
Non persistent connections:
Beta9: 8,810
1.3.18.Final: 6,578
1.3.18.Final + XNIO 3.3.6.Final-SNAPSHOT: 10,285
When under heavy load the accept thread approach performs much better than the old approach (which was what we saw in Specj), however the XNIO bug was causing problems.
Jim, because you saw a much greater performance loss that I did would you be able to re-run some of these tests with my XNIO changes and verify that this also fixes the issue for you (ideally using multiple ab instances to really load the machine)? If there are still problems I would like to know what sort of hardware you are seeing this on.
Stuart
----- Original Message -----
> From: "Andrig T. Miller" <anmiller at redhat.com>
> To: "Jim Crossley" <jim at crossleys.org>
> Cc: "Stuart Douglas" <sdouglas at redhat.com>, undertow-dev at lists.jboss.org
> Sent: Thursday, 10 March, 2016 8:28:37 AM
> Subject: Re: [undertow-dev] Loss of perfomance between 1.3.0.Beta9 and 1.3.18.Final
>
> Stuart,
>
> I'm not sure what this undertow-speed app does, but I'm nervous that tuning
> for it, may undo some of the improvements we made in the performance lab.
> One thing I would suggest though, is using perf on Linux and creating a
> flamegraph for Beta9 and the Final. It's likely that some methods that were
> being inlined are no longer being inlined, and the flamegraphs and the
> underlying perf data will show that. In order to use perf you have to set
> the JVM parameter to preserve frame pointers:
>
> -XX:+PreserveFramePointer
>
> Ping anyone from the performance team, and they can help you with the setup
> of perf, and generating the flame graphs.
>
> Andy
>
> ----- Original Message -----
>
> > Hi Stuart,
>
> > Toby asked me to try on my machine, and I see an even bigger
> > throughput disparity. I'm using his test app:
> > https://github.com/tobias/undertow-speed
>
> > In one shell I run 'mvn clean compile exec:java' and in another I run
> > './bench-avg.sh' and I get this output:
>
> > jim at minty ~/apps/undertow-speed $ ./bench-avg.sh
> > Requests per second: 14717.03 [#/sec] (mean)
> > Requests per second: 14527.32 [#/sec] (mean)
> > Requests per second: 14288.32 [#/sec] (mean)
> > Requests per second: 14375.64 [#/sec] (mean)
> > Requests per second: 14653.08 [#/sec] (mean)
> > Average: 14512
>
> > Then I run 'mvn clean compile exec:java -Pbeta9' in the first shell
> > and re-run bench-avg.sh. I get this:
>
> > jim at minty ~/apps/undertow-speed $ ./bench-avg.sh
> > Requests per second: 24069.72 [#/sec] (mean)
> > Requests per second: 25002.35 [#/sec] (mean)
> > Requests per second: 24885.36 [#/sec] (mean)
> > Requests per second: 25261.30 [#/sec] (mean)
> > Requests per second: 24800.82 [#/sec] (mean)
> > Average: 24803.4
>
> > As you can see, quite a bit more than 7%, beta9 yields almost 70%
> > better throughput for me!
>
> > I set the option you suggested for 1.3.18 and I get slightly better
> > numbers:
>
> > jim at minty ~/apps/undertow-speed $ ./bench-avg.sh
> > Requests per second: 15749.52 [#/sec] (mean)
> > Requests per second: 15309.83 [#/sec] (mean)
> > Requests per second: 15909.15 [#/sec] (mean)
> > Requests per second: 16228.10 [#/sec] (mean)
> > Requests per second: 16118.84 [#/sec] (mean)
> > Average: 15862.6
>
> > But nowhere close to beta9.
>
> > Can you clone his app and reproduce locally?
>
> > Thanks,
> > Jim
>
> > On Tue, Mar 8, 2016 at 6:35 PM, Stuart Douglas <sdouglas at redhat.com> wrote:
> > > Can you re-run but with the following setting:
> > >
> > > .setServerOption(UndertowOptions.NO_REQUEST_TIMEOUT, -1)
> > >
> > > The default changed between these versions, so now idle connections will
> > > eventually be timed out (otherwise browsers can hold connections for a
> > > very time long which was causing people to have issues with FD
> > > exhaustion).
> > >
> > > Stuart
> > >
> > > ----- Original Message -----
> > >> From: "Stuart Douglas" <sdouglas at redhat.com>
> > >> To: "Toby Crawley" <toby at tcrawley.org>
> > >> Cc: undertow-dev at lists.jboss.org
> > >> Sent: Monday, 7 March, 2016 10:59:27 AM
> > >> Subject: Re: [undertow-dev] Loss of perfomance between 1.3.0.Beta9 and
> > >> 1.3.18.Final
> > >>
> > >> This is not a known issue, I will investigate.
> > >>
> > >> Stuart
> > >>
> > >> ----- Original Message -----
> > >> > From: "Toby Crawley" <toby at tcrawley.org>
> > >> > To: undertow-dev at lists.jboss.org
> > >> > Sent: Saturday, 5 March, 2016 7:29:00 AM
> > >> > Subject: [undertow-dev] Loss of perfomance between 1.3.0.Beta9 and
> > >> > 1.3.18.Final
> > >> >
> > >> > Is there a known decrease in throughput (measured with req/s)
> > >> > between 1.3.0.Beta9 and 1.3.18.Final? We currently ship the former
> > >> > with Immutant, and were looking at upgrading to the latter in the next
> > >> > release, but noticed a decrease in throughput with a simple Clojure
> > >> > benchmark app.
> > >> >
> > >> > I have replicated the basics of our benchmark app in Java[1], and saw
> > >> > a
> > >> > decrease in req/s between the two versions of ~7% when testing with ab
> > >> > and averaging the output of several runs.
> > >> >
> > >> > Is there something that changed between those versions that is known
> > >> > to have reduced performance?
> > >> >
> > >> > - Toby
> > >> >
> > >> > [1]: https://github.com/tobias/undertow-speed
> > >> > _______________________________________________
> > >> > undertow-dev mailing list
> > >> > undertow-dev at lists.jboss.org
> > >> > https://lists.jboss.org/mailman/listinfo/undertow-dev
> > >> >
> > >> _______________________________________________
> > >> undertow-dev mailing list
> > >> undertow-dev at lists.jboss.org
> > >> https://lists.jboss.org/mailman/listinfo/undertow-dev
> > >>
> > > _______________________________________________
> > > undertow-dev mailing list
> > > undertow-dev at lists.jboss.org
> > > https://lists.jboss.org/mailman/listinfo/undertow-dev
> > _______________________________________________
> > undertow-dev mailing list
> > undertow-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/undertow-dev
>
More information about the undertow-dev
mailing list