Re: When and where to close the connection in a struts-web-application?

Indeed that is what I noticed too. After playing around with ab -c 10 -n 
1000, I had "too many open files" and therefore noticed the below behaviour.

Anyway, I've created a PlugIn for struts which gets started as soon as 
my struts application starts and gets destroyed when struts is getting 
destroyed. And creates a database upon startup, close's it at the end 
and provides static accessors to the instance.

If anyone is interested in it, I can post it to this list.

Best regards,

Arjen


Roy Ladner wrote:

> I've notice that when the database connection is not closed, the number 
> of open connections continues to grow  as 
> ExternalDatabase.openDatabase(...) is repeatedly called until an out of 
> memory error occurs.  Is this an operator error or is there an issue in 
> the Ozone code that should be addressed?
> 
> 
> Per Nyfelt wrote:
> 
>>Hi Arjen,
>>
>>Use application scope (or equivalent) instead of session.
>>
>>ExternalDatabase handles pooling and simultaneous access in itself. See FAQ 
>>for more details.
>>
>>Best regards,
>>Per
>>
>>måndagen den 8 mars 2004 17.52 skrev Arjen van der Meijden:
>>  
>>
>>>Hi list,
>>>
>>>I'm building a web application with Struts and it uses ozone as its
>>>backend database. Well thats easily done and what I have works quite nice.
>>>
>>>There is one problem however I don't know where or when to close the
>>>connection to the ozone database. I can easily open one as soon as I
>>>need some data, but that data will be put into the "request scope" and
>>>then the Struts-ActionServlet forwards the control to some jsp-file (or
>>>another Action).
>>>
>>>So what I do now is something like:
>>>public ... execute(...)
>>>{
>>>   ExternalDatabase db = ExternalDatabase.openDatabase(...);
>>>   Object someObject = db.objectForName("someName");
>>>
>>>   request.setAttribute("someObject", someObject);
>>>   return actionMapping.findForward("success");
>>>}
>>>
>>>And the control gets forwarded to some jsp, that may do something like:
>>><jsp tags>
>>><bean:write name="someObject" property="someProperty" />
>>><some more jsp tags>
>>>
>>>And when the entire operation is done, the database-connection should be
>>>close()-ed. But at that time, I have no direct control over the
>>>operation anymore... and so the number of open connections increases at
>>>every pageview.
>>>
>>>I see a few solutions to this, but don't know which is best or even more
>>>exist:
>>>- Make a static singleton reference to an ExternalDatabase object; there
>>>won't be much connectionpooling anymore, but you can be certain there
>>>will be only one databaseconnection. It may perform quite badly because
>>>there won't be multiple connections available at any time?
>>>
>>>- Make some kind of value objects, create value objects via the proxies
>>>and close the connection as soon as the value objects are created and
>>>stored in the request-scope. This really doesn't have my preference,
>>>even though it may be saver and "better" in the application design (it
>>>is also much more work).
>>>
>>>Thanks in advance and best regards,
>>>
>>>Arjen
>>>
>>>
>>>PS, John Dixon, I forgot to thank you for your advise/answer on my
>>>previous e-mail.





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