[Seaside] Concurrent requests from multiple sessions

Benoit St-Jean bstjean at yahoo.com
Tue Mar 10 16:21:39 UTC 2015

One more thing to check : could it be possible that your query is getting blocked because of lock escalation?  Which isolation level are you using?
Benoit St-Jean
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"A standpoint is an intellectual horizon of radius zero".  (A. Einstein)
      From: Sebastian Sastre <sebastian at flowingconcept.com>
 To: Seaside - general discussion <seaside at lists.squeakfoundation.org> 
 Sent: Tuesday, March 10, 2015 11:57 AM
 Subject: Re: [Seaside] Concurrent requests from multiple sessions
Hi Ondrej,
are you using an ODBC connection? What comes to mind is to check if maybe the FFI call to ODBC or whatever driver you are using to get into DB2 is blocking the VM running that image until it gets the answer.
Whatever the case, you seem to need to scale your app horizonatally with many images.
At least that’s how I do it.
Other than that, there is something that you probably don’t want to even hear about but for what’s worth: a REST backend and a single page application scales really well due to clients’ CPU dividing load and RESTful backends having way better parallelisation
LinkedIn: http://www.linkedin.com/in/sebastiansastregithub: https://github.com/sebastianconcept

On Mar 6, 2015, at 7:17 AM, wilwarin <Ondrej.Altman at seznam.cz> wrote:
Hi all,

Currently we are developing a web application in Seaside, and it is
necessary for us to work in VAST. The application runs as a Windows service,
and for a few days we are facing the following issue:

- At one moment there are two users (let's call them 'A' and 'B') logged in
in the application, so we have two different sessions.
- 'A' requests a page with a long list of objects obtained from DB2, so it
takes a number of seconds to get the results.
- Less than one second after 'A''s request, 'B' requests another page, for
instance an easy static page.
- For the time the 'A''s request is handled, the 'B''s browser window
freezes and waits for those number of seconds mentioned above.

We searched really a lot, but still the results are not what we would
expect. This issue makes as confused, because in the future the application
should serve hundreds of users with very similar combinations of requests.

We didn't know, where our problem lies, so we tried a similar test with a
single page with a difficult calculation inside. Then we tried the same in
Pharo to exclude the problem in VAST. Both with the same results.

Is there anything we are missing? What should we do to achieve a parallel
(or kinda better) processing of requests?

Thank you very much for your responses.


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