Hi all, esp Marcus,
I too have been running Load tests, I also noticed that 'something' was
happening regularly to slow the response. I hadn't gotten round to checking
the code though (the testing machines are isolated - 0 access from/to my dev
station).
I saw your patch and rejoiced ;) but it's taken the response of some of my
pages from a couple of hundred milliseconds to over 5! I've not yet looked
at _what_ your patch did, but have you seen a similar increase in time?
J.
> -----Original Message-----
> From: Carsten Ziegeler [mailto:[EMAIL PROTECTED]]
> Sent: Monday, 20 August 2001 7:57 am
> To: [EMAIL PROTECTED]
> Subject: AW: [C2] sitemap creation threading issue ?
>
>
> Hi Marcus,
>
> thanks for your patch. I applied it, please cross check :-)
>
> Carsten
>
> > -----Ursprungliche Nachricht-----
> > Von: Marcus Crafter [mailto:[EMAIL PROTECTED]]
> > Gesendet: Samstag, 18. August 2001 22:41
> > An: Cocoon Developers Mailing List
> > Betreff: [C2] sitemap creation threading issue ?
> >
> >
> > Hi *,
> >
> > Hope all is well.
> >
> > Michael and I have spent the day testing our C2 application with
> > LoadRunner and have potentially uncovered a threading
> problem during
> > sitemap creation.
> >
> > We're not experts with the code but from our understanding the
> > following is happening, please let us know if we are
> right/wrong:
> >
> > There seems to be a problem with the getHandler()
> method, located in
> > the sitemap Manager class (line 154). getHandler() attempts
> > to access a
> > sitemap handler object for each request for processing. If
> > the handler
> > object is not available it creates one, causing the
> sitemap to be
> > generated.
> >
> > We've noticed under load, that many handler objects are
> created for
> > the same sitemap. This is because getHandler() does not
> protect the
> > following lines:
> >
> > Handler sitemapHandler = (Handler)sitemaps.get(source);
> >
> > and
> >
> > sitemaps.put(source, sitemapHandler);
> >
> > as a critical area.
> >
> > If multiple concurrent threads pass through
> getHandler() which are
> > requests for resources from the same sitemap, the first line
> > above will return null multiple times causing the same
> sitemap to be
> > compiled several times, each by individual Handler objects.
> >
> > This happens because sitemaps.put() executes after each
> > sitemap handler
> > object is created (which can take time for large sitemaps),
> > and cannot
> > prevent other incoming threads from waiting until it
> adds the newly
> > created handler object into the 'sitemaps' hashmap.
> >
> > When we synchronized the getHandler method to protect the
> > getting/setting of the sitemaps hashmap, we saw that the sitemap
> > handler object was created only once, and that the application
> > performed much better under load. Previously the same
> > sitemap handler
> > object was created as many times as we had simultaneous threads
> > make requests.
> >
> > Attached is a diff of the change we made. There might
> be a better
> > solution as the Handler class seems to be built to
> handle this, it's
> > just that the allocation of a new Handler objects per
> > sitemap, defeats
> > it's internal multi-thread logic.
> >
> > Any comments/thoughts/suggestions ?
> >
> > Cheers,
> >
> > Marcus
> >
> > --
> > .....
> > ,,$$$$$$$$$, Marcus Crafter
> > ;$' '$$$$: Computer Systems Engineer
> > $: $$$$: Open Software Associates GmbH
> > $ o_)$$$: 82-84 Mainzer Landstrasse
> > ;$, _/\ &&:' 60327 Frankfurt Germany
> > ' /( &&&
> > \_&&&&' Email : [EMAIL PROTECTED]
> > &&&&. Business Hours : +49 69 9757 200
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> >
>
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