[Zope] Zope Memory Problem

[Douwe Osinga]

Hi Dieter,

Thanks for the tips.

> Douwe Osinga wrote at 2003-10-29 10:52 +0100:
>  > I am experiencing problems with the amount of memory Zope is using.
>  > I'm using Zope 2.6.2 and Windows 2000 server. Now, things work fine
>  > for days and then suddenly something goes wrong and the amount of
>  > memory in use by Zope increases until 2Gb or so and the process
>  > stops responding completely.
>  > 
>  > My current theory is that this happens when some requests take very
>  > long to answer (ie. 1 minute or so).

 
> I see 3 potential causes (there may be more):
> [...]
>   *  you have memory leaks -- pieces of code that leak (usually)
>      small amounts of memory. Over time, you loose more and more
>      memory.
>      You can use Shane's "LeakFinder" product to track this down.
I installed the product and found out that when the memory consumption
grows, I also get a *lot* of instances of IOBucket and OOBucket and
similar named objects, but mostly DateTime objects. Since I had never
heard of the first kind of objects and they sounded rather like basic
building blocks, I put a patch on the DateTime. It gave me references
to pieces of code that without a miss were doing lookups from the
ZCatalogue, i.e. a ZClass that was instantiated with something like:

   zobj = context.Catalog.getobject( catitem.data_record_id_ )

where zobj has properties of DateTime type, so that might be the problem.
The logs actually suggest that this statement is then executed for 300
times a second, though the surrounding code does not seem to do that.

Now, the ZClass is question is also derived from a class I created myself
in Python, so that is probably where the memory leak is to be found. The
thing is that I don't know what I'm looking for: how do I create a
memory leak in Python? Doesn't the garbage collector clear these things?

Any help is much appreciated.

Douwe Osinga