[Seaside] Re: Concurrent requests from multiple sessions

wilwarin Ondrej.Altman at seznam.cz
Tue Mar 10 10:15:12 UTC 2015

Hi all,

please excuse my inactivity, now I would like to summarize all above, and to
ask you maybe for a few last answers and advices.

Regarding to mentioned DB2, as I assumed, database is definitely not an
issue, so I am sorry for my inaccuracy in my first post. At the moment we
are sure that there is no block from the database side (we can see the block
in data processing). Thank you guys for your solution proposals.

> The only Seaside limitation I'm aware of is a lock around every 
> session. So only one request of 'A' can be processed at any given 
> time. However this should not affect any other users. The lock is 
> there because sessions and components are mutable. Use the code from 
> Sven to verify Seaside and your webserver are not the issue. 

This is the behavior we assumed, this (max. one request per session at any
time) has to be, and actually is, enough. However we are really surprised,
that other users are affected. And by our investigation they are always
affected by every concurrent request, no matter how difficult it is. 

( I tried Sven's code and it is possible to do another work during waiting,
it is OK. )

> But that problem (not being able to process concurrent requests) is 
> certainly not inherent to Seaside or Pharo. If that were the case we 
> should all stop using it. 

Hopefully I understand, so it is not the case. If I am correct, it means
that in Seaside it is necessary to solve similar situations with different
access. In case of for example difficult server-side calculation (or
processing of big amount of data), we have to count on a possible problem
with concurrent requests from multiple sessions. Am I right? Or, if not,
where could the problem lay?

As I wrote, we are working in VAST - I tried to simulate the same problem in
Pharo with the same result, so I think in this case it does not matter much.
Regarding to Apache (or, when we run it from code), everything is in default
configuration. Database is not an issue. For me it looks like everything,
that I wrote here, is a standard behavior of application build on Seaside =>
the application which has to serve not-so-easy concurrent requests has to
use some way around (multiple images & load balancing, parallelization of
processes, ...). Please correct me if I am wrong.

Guys, could you please tell me what I am missing?

Maybe I can imagine, that the application we are developing is not a
'standard' Seaside app (in the sense of data amount and its difficult
server-side processing). Then I believe it would require a non-standard
architecture (according to that all, is Seaside still the path we can/should
follow?). It is our problem, we do not know about a reliable way to do that
- and this is the reason, why I am asking here.

What would you recommend? 

Thank you again for your time, and thank you for your responses in advance.


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