[lxml-dev] [lxml][objectify] optimization questions

[Holger Joukl]

Stefan Behnel <behnel_ml at gkec.informatik.tu-darmstadt.de> schrieb am
24.10.2006 00:23:54:

> Hi again,
>
> I rewrote the current recursive string printing implementation to use a
real
> iterator for attribute access, which also lead to much shorter code in
_Attrib
> (after a cleanup). This should remove the difference you see, although
moving
> towards the slower variant. However, if it worked, this means that the
> elements are immediately garbage collected, which is the right thing to
do
> from a memory perspective.
>
> Please test on your machine a) if the two code snippets still differ in
> performance and b) if the new implementation resulted in any
> noticeable slow down.

I can confirm
a) no performance difference between recursive element printing and "manual
element access" any more
b) no significant slow down
using the little timeit snippets for benchmarking.

> If you feel ambitious, take a look at the benchmark directory and try to
come
> up with a new benchmark suite "bench_objectify.py". The benchmark
framework
> makes new benchmarks extremely easy to write and the four test XML trees
> should be well suited for objectify already.

Will take a look.

Some more need for clarification:
If I understand correctly the lxml element proxy only speeds up things if
- I hold a python reference to the element object or
- a circular reference to the element in question prevents it from being
gc-ed
To speed up my usecase I could force-create and hold python references to
every node before
starting to operate on the tree.

Would it also be possible to modify objectify in a way that the lifespan of
the python _Element, once it has been instantiated, is tied to the
existence of the
underlying _c_node (xmlNode)?

Holger

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