[undertow-dev] Unable to concurrently use all available IO Threads under load on Red Hat

[Bill O'Neil]

Did you try setting the concurrency level much higher than 8 like I
suggested earlier? You are probably having multiple connections assigned to
the same IO threads.

On Wed, Jul 25, 2018 at 12:26 PM, R. Matt Barnett <barnett at rice.edu> wrote:

> Corrected test to resolve test/set race.
>
>
> https://gist.github.com/rmbarnett-rice/1179c4ad1d3344bb247c8b8daed3e4fa
>
>
> I've also discovered this morning that I *can* see 1-8 printed on Red
> Hat when I generate load using ab from Windows, but only 1-4 when
> running ab on Red Hat (both locally and from a remote server).  I'm
> wondering if perhaps there is some sort of connection reuse shenanigans
> going on.  My assumption of the use of the -c 8 parameter was "make 8
> sockets" but maybe not.  I'll dig in and report back.
>
>
> -- Matt
>
>
> On 7/24/2018 6:56 PM, R. Matt Barnett wrote:
> > Hello,
> >
> > I'm experiencing an Undertow performance issue I fail to understand.  I
> > am able to reproduce the issue with the code linked bellow. The problem
> > is that on Red Hat (and not Windows) I'm unable to concurrently process
> > more than 4 overlapping requests even with 8 configured IO Threads.
> > For example, if I run the following program (1 file, 55 lines):
> >
> > https://gist.github.com/rmbarnett-rice/668db6b4e9f8f8da7093a3659b6ae2b5
> >
> > ... on Red Hat and then send requests to the server using Apache
> > Benchmark...
> >
> >       > ab -n 1000 -c 8 localhost:8080/
> >
> > I see the following output from the Undertow process:
> >
> >       Server started on port 8080
> >
> >       1
> >       2
> >       3
> >       4
> >
> > I believe this demonstrates that only 4 requests are ever processed in
> > parallel.  I would expect 8.  In fact, when I run the same experiment on
> > Windows I see the expected output of
> >
> >       Server started on port 8080
> >       1
> >       2
> >       3
> >       4
> >       5
> >       6
> >       7
> >       8
> >
> > Any thoughts as to what might explain this behavior?
> >
> > Best,
> >
> > Matt
> >
> > _______________________________________________
> > undertow-dev mailing list
> > undertow-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/undertow-dev
>
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