How to implement clone method for the C++ class with some methods overriden in python?

ibelyaev · April 2, 2024, 12:27pm

Dear Experts

I am using in PyROOT some (C++) classes with soem method overrided inn python.
e.g. RooAbdPdf with evaluate method implemented in python. Since RooAbsPdf::clone
is called from C++, reimplementation of clone in python is not a well defined task, but I’ve got some workhg ad-hoc solution, not elegant but suitable for my need, see [thiss gitst]
(problme with pythoinns PDF for new ROOT/cppyy · GitHub)

Recenlty, new cppyy/PyROOT (ROOT 6.31/01) enters the game (I am using LCG dev3 cvmfs nightly builds), and, as expeected, my fragile solutuon is not working anymore.
Acrually, the program still works, but it hangs at the exit…

Is there some known/recommended solution for such kind of problems?

Thank you inn advance for any useful hints!

jonas · April 2, 2024, 1:01pm

Hi @ibelyaev,

thanks for the report! There is some infinite loop going on, I hope to fix it with this PR:

github.com/root-project/root

PyROOT] Fix infinite loop in `TMemoryRegulator::ClearProxiedObjects()`

root-project:master ← guitargeek:infinite_loop

opened 10:25AM - 02 Apr 24 UTC

guitargeek

+54 -100

There is an infinite loop in `PyROOT::TMemoryRegulator::ClearProxiedObjects()`:… ```C++ while (!fObjectMap.empty()) { auto elem = fObjectMap.begin(); auto cppobj = elem->first; auto klassid = elem->second; auto pyclass = CreateScopeProxy(klassid); auto pyobj = (CPPInstance *)MemoryRegulator::RetrievePyObject(cppobj, pyclass); if (pyobj && (pyobj->fFlags & CPPInstance::kIsOwner)) { ... } else { // Non-owning proxy, just unregister to clean tables. // The proxy deletion by Python will have no effect on C++, so all good MemoryRegulator::UnregisterPyObject(pyobj, pyclass); } } ``` In the second code branch, the object is not removed from the `fObjMap, causing an infinite loop because `fObjectMap` never gets empty. Although this seems like an obvious logic error, this was only noticed after the cppyy upgrade. Probably the code path was not hit before. Addresses https://github.com/root-project/root/issues/15085#issuecomment-2031363812. This PR also includes a second refactoring commit to reduce the amount of C++ code in PyROOT. **This could maybe also fix the problem with the distributed RDataFrame test timeouts!**

Indeed, I’m surprised that implementing the clone() method like this even works at all! This is not bad, but indeed a little fragile.

Have you tried implementing a RooAbsPdf class that takes a std::function as an input? Python functions can be implicitly converted to std::function in cppyy. Maybe that is the better was two wrap Python functions in RooFit objects?

Cheers,
Jonas

system · April 16, 2024, 1:01pm

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.