On 2018-05-30 07:45:07 +0200, dieter wrote: > "Peter J. Holzer" <hjp-pyt...@hjp.at> writes: > > On 2018-05-26 07:38:09 +0200, dieter wrote: > >> But, in general, you are right: you cannot reconstruct complete > >> call trees. The reason is quite simple: maintaining information > >> for the complete caller ancestry (rather than just the immediate > >> caller) is expensive (both in terms of runtime and storage). > >> Profiling usually is used as a preparation for optimization. > >> Optimization has the greatest effects if applied to inner loops. > >> And for the analysis of inner loops, complete call tree information > >> is not necessary. > > > > I disagree. I have used Tim Bunce's excellent perl profiler > > (Devel::NYTProf, for the two people here who also use Perl and don't > > already know it), which does record whole call trees, and this is very > > useful. You not only see that a function is called 1.5 million times, > > you also see where it is called (not just from which functions, but from > > which lines) and how much time is spent in calls from each location. > > Often this allowed me find ways to avoid calling a function altogether > > or prevented me from chasing down the wrong rabbit hole. > > If the profile information is sampled for the call location (rather then > the call function), you still do not get the "complete call tree". > If you want to get results based on call paths (rather than the immediate > caller), the sampling must (in general) sample for call paths (and > not only the immediate caller) -- which means, you must implement > your own profiler.
I don't dispute that you would have to implement your own profiler.
I do dispute that this information is useless. As I said, I have used
Devel::NYTProf for Perl, and after using that cProfile feels like a huge
step backwards. There are some areas where Python is ahead of Perl, but
the profiler definitely isn't one of them :-(.
hp
--
_ | Peter J. Holzer | we build much bigger, better disasters now
|_|_) | | because we have much more sophisticated
| | | h...@hjp.at | management tools.
__/ | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
signature.asc
Description: PGP signature
-- https://mail.python.org/mailman/listinfo/python-list
