[Python-Dev] Disabling cyclic GC in timeit module

[Antoine Pitrou]

> >
> > In CPython, looking for reference cycles is a parasitic task that
> > interferes with what you are trying to measure. It is not critical in
> > any way, and you can schedule it much less often if it takes too much
> > CPU, without any really adverse consequences. timeit takes the safe way
> > and disables it completely.
> >
> > In PyPy, it doesn't seem gc.disable() should do anything, since you'd
> > lose all automatic memory management if the GC was disabled.
> >
> 
> it disables finalizers but this is besides the point. the point is
> that people use timeit module to compute absolute time it takes for
> CPython to do things, among other things comparing it to PyPy. While I
> do agree that in microbenchmarks you don't loose much by just
> disabling it, it does affect larger applications. So answering the
> question like "how much time will take json encoding in my
> application" should take cyclic GC time into account.

If you are only measuring json encoding of a few select pieces of data
then it's a microbenchmark.
If you are measuring the whole application (or a significant part of it)
then I'm not sure timeit is the right tool for that.

Regards

Antoine.