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MyASPN >> Mail Archive >> zodb-dev
zodb-dev
Re: [ZODB-Dev] Cache Query (why doesn't RAM usage ever drop?)
by Chris Withers other posts by this author
Oct 30 2002 2:00PM messages near this date
Re: [ZODB-Dev] Cache Query (why doesn't RAM usage ever drop?) | Re: [ZODB-Dev] Cache Query (why doesn't RAM usage ever drop?)
Toby Dickenson wrote:
> >I just hit the help button:
> >http://x/HelpSys?help_url=/Control_Panel/Products/OFSP/Help/Database-Manage
> >ment_Database.stx
>  
>  I dont see anything wrong with the 2.6 version????

Hmmm, I'm actually using the Alpha here, did you fix it up after that?

>  A malicious script? yes.  I think this is a bogus argument for a change to 
>  ZODB; a malicious script could also bring the server down by creating large 
>  numbers of non-persistent objects

Not malicious, consider this:

for brain in context.some_catalog(an_index='fish'):
   object = brain.getObject()
   object.doSomeMaintenence()

...now if an_index goes walkies, you've just loaded all the obejcts you've 
cataloged into memory by mistake.

>  A well-intentioned script? you just need to call the garbage collecter 
>  intermittantly (plus use subtransactions if you are modifying large numbers 
>  of objects) and everything will be happy.

Can you do either of those from Script (Python)'s?

>  The problem is not the hardness of the limit, but rather that the limit is 
>  applied at the right time. Any automatic enforcement mid-transaction is 
>  liable to cause problems (for example, think about _v_ attributes)

how would raising a MemoryError (as happens when you run of RAM for real) affect 
these?

>  If it is using Zope's 'File' object then the 500k block-o-bytes will have been 
>  split into 7 64k chunks, and each chunk stored in a ZODB object.

Oh, cool, didn't know that :-)

>  I can suggest a change to your indexing loop that will make this happen 
>  automatically. Would that help? ; -)

What would the change be?

cheers,

Chris


_______________________________________________
For more information about ZODB, see the ZODB Wiki:
http://www.zope.org/Wikis/ZODB/

ZODB-Dev mailing list  -  ZODB-Dev@[...].org
http://lists.zope.org/mailman/listinfo/zodb-dev
Thread:
Chris Withers
Chris Withers
Chris Withers
Toby Dickenson
Chris Withers
Toby Dickenson
Toby Dickenson
Shane Hathaway
Shane Hathaway
Shane Hathaway
Christian Reis
Tim Peters
Chris Withers
Chris Withers
Chris Withers
Shane Hathaway
Shane Hathaway
Shane Hathaway
Toby Dickenson
Jeremy Hylton
Tim Peters

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