Chris Withers schrieb:
Hi Jim,
I'm wondering if you can still remember the rational behind the cache code at around lines 355-387 of:
http://svn.zope.org/Zope/trunk/lib/python/Shared/DC/ZRDB/DA.py?rev=68158&vie...
This code is pretty old (checked in 5th Dec 1997) but has started causing a few people problems under high load:
http://mail.zope.org/pipermail/zope-db/2006-September/004684.html http://www.zope.org/Collectors/Zope/2212
In particular:
- in line 368, why is len(cache)>max_cache/2 used as a trigger to start cache clearing? (the /2 in particular)
- does it matter that IOBTree.Bucket has gone away and that tcache is now a simple dictionary? It certainly seems to make the keys.reverse() on line 370 superfluous and the keys[-1]<t on line 371 less reliable.
More generally, do you or does anyone else have any attachment to this code or would anyone mind if I ripped it out and replaced it with something simpler, with more comments and unit tests?
I have a replacement started, which uses Cacheable mixin instead. Advantage is, with RAM Cache Manager you can see the hits your method cause and invalide the cache per object. I also introduced a execution time treshold, so you can configure to only cache runtimes say above 1 sec, leaving more room for long running queries. I think I should packe up what I have now (rough edges) so you can have a look at it. Tino.