What can I do to maximize the peformance of a dtml-in statement?
When iterating over a 2000 row database query, it takes about 20
seconds - time mostly spent doing security checks, and calling
__getitem__ in DT_InSV.py. Is the performance of dtml-in just slow?
-Brett
Another performance consideration with looping in DTML is that whatever
is in your DTML block is reinterpreted each time through. Although it is
parsed (hopefully) only the first time through, this overhead is still
considerable when multiplied over 2000 rows. You are essentially using
an interpreter (Python) as an interpreter for DTML. I would seriously
consider moving this entire operation (query, iteration and html
generation) to native Python if performance is a big consideration.
We have had similar performance problems with the first version of our
Content Management demo. It used both dtml-in loops and ZClasses (with other
ZCLasses as base classes) heavily. The combination of the both can be very
efficient in slowing down Zope. I remember the first versions of Martijn
Faassen's XML-Widgets that had a similar performance problem. The reason is
that in addition to the dtml-in overhead ZClasses take a lot of time for
acquiring from their containers and inheriting from their "base classes" as
all the inheritance stuff is only simulated - in fact almost everything is
just stored in property sheets and has to be processed by the security
engine if I got it right.
In Python these problems go away. Maybe it is time for a good
reimplementation of ZClasses, inlcuding the creation of REAL Python classes
in the filesystem on the fly.
BTW: Does anybody know if the Zope Page Templates (ZPT) parser is faster
with looping than the DTML one?
Cheers,
Joachim.
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