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Posted to dev@cocoon.apache.org by Alfredas Chmieliauskas <al...@sseriga.edu.lv> on 2002/06/28 22:49:36 UTC
IMPORTANT: Major Bug in XMLDBSource
Hi all,
this bug relates to every cocoon and xindice versions available, thus it
definately concerns you, if you're using xmldb and accessing it through
XMLDBSource (xmldb: pseudo-protocol).
Short history:
We're developing a project that is based on cocoon + xindice and, for a
while, we were wonering why using cocoon and xindice causes such high
memory consumption, which on higher loads terminates xindice with an
OutOfMemoryError. Moreover, similar problems have been reported to both
lists some time ago.
No doubt about cocoon, I was blaming xindice for the error (that corba
implementation seemed suspicious from the very begining). However, after
some memory profiling done for both cocoon and xindice, I got myself to
check out and revise the XMLDBSource source-code, which turned out to be
the cause of the problem in the end.
The error is as follows:
Every new request to the database creates new XMLDBSource, which in turn
registers a database implementation (driver)
(DatabaseManager.registerDatabase(...)) *every time* it is created.
Thus after 15 requests to your databse you have 15 database client
implemetations loaded by your VM.
You can guess what happens when you have 150 requests, can't you? ;-)
Quick-fix:
A reasonable and quick fix for the problem would be to move the
connect() method from the XMLDBSource to the XMLDBSourceFactory.
Why, on earth, would one bother about the connection in the source
methods, when it is the major concern for the SourceFactory, i wonder?
Proposal:
It seems that commonly the rdbms drivers are loaded through the
cocoon.xconf or web.xml on servlet startup (hsqldb, for example?). Why
not treat the xmldb drivers the same way?
I hope I saved some time (and memory ;-) for some of you,
Alfredas
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Re: IMPORTANT: Major Bug in XMLDBSource
Posted by Alex McLintock <al...@OWAL.co.uk>.
At 21:49 28/06/02, Alfredas Chmieliauskas wrote:
> > this bug relates to every cocoon and xindice versions available, thus
> it definately
> > concerns you, if you're using xmldb and accessing it through XMLDBSource
> (xmldb: pseudo-protocol).
[memory leak description removed]
Thanks very much for spotting that. It seems to coincide with my
experiences of running out of memory when making lots of Cocoon->XIndice calls.
I am about to go on holiday but if you can't find anyone to fix this in the
next couple of weeks please email me and I will see what I can do. What you
seem to be proposing is a Connection Pool for XMLDB in the same way as we
have connection pools for database connections. That can't be too hard can
it? :-)
Alex McLintock
Openweb Analysts Ltd, London: Software For Complex Websites
http://www.OWAL.co.uk/
Free Consultancy for London Companies thinking of Open Source Software.
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Re: IMPORTANT: Major Bug in XMLDBSource
Posted by Stephan Michels <st...@apache.org>.
On Fri, 28 Jun 2002, Alfredas Chmieliauskas wrote:
> Hi all,
>
> this bug relates to every cocoon and xindice versions available, thus it
> definately concerns you, if you're using xmldb and accessing it through
> XMLDBSource (xmldb: pseudo-protocol).
>
> Short history:
> We're developing a project that is based on cocoon + xindice and, for a
> while, we were wonering why using cocoon and xindice causes such high
> memory consumption, which on higher loads terminates xindice with an
> OutOfMemoryError. Moreover, similar problems have been reported to both
> lists some time ago.
>
> No doubt about cocoon, I was blaming xindice for the error (that corba
> implementation seemed suspicious from the very begining). However, after
> some memory profiling done for both cocoon and xindice, I got myself to
> check out and revise the XMLDBSource source-code, which turned out to be
> the cause of the problem in the end.
>
> The error is as follows:
> Every new request to the database creates new XMLDBSource, which in turn
> registers a database implementation (driver)
> (DatabaseManager.registerDatabase(...)) *every time* it is created.
>
> Thus after 15 requests to your databse you have 15 database client
> implemetations loaded by your VM.
> You can guess what happens when you have 150 requests, can't you? ;-)
>
> Quick-fix:
> A reasonable and quick fix for the problem would be to move the
> connect() method from the XMLDBSource to the XMLDBSourceFactory.
> Why, on earth, would one bother about the connection in the source
> methods, when it is the major concern for the SourceFactory, i wonder?
>
> Proposal:
> It seems that commonly the rdbms drivers are loaded through the
> cocoon.xconf or web.xml on servlet startup (hsqldb, for example?). Why
> not treat the xmldb drivers the same way?
>
> I hope I saved some time (and memory ;-) for some of you,
>
> Alfredas
Thanks for your comment. I have tried to refactoring the
XMLDBSourceFactory. The new version in the scratchpad.
Can please test it?!
_______________________________________________________________________
Stephan Michels EMail: stephan@apache.org
ICQ: 115535699 Tel: +49-030-314-21583
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