Problem 2501

Summary:	Concurrency issues with getenv calls in ParticleHP on Visual Studio
Product:	Geant4	Reporter:	Sergio Losilla <sergio.losilla>
Component:	processes/hadronic/models/neutron_hp	Assignee:	dennis.herbert.wright
Status:	RESOLVED FIXED
Severity:	normal
Priority:	P4
Version:	11.0
Hardware:	All
OS:	All

Description Sergio Losilla 2022-07-21 14:04:56 CEST

Applications using ParticleHP built on Visual Studio 2022 suffer a significant slowdown when running on 64 threads.

The culprit seems to be the numerous calls to std::getenv. The Visual C++ standard library implementation of std::getenv seems to be thread-safe, and the locks cause a very noticeable slowdown on a larger number of cores.

The main culprits seem to be:
* G4PHPTEST2, read eg in G4ParticleHPContAngularPar::BuildByInterpolation (source\processes\hadronic\models\particle_hp\src\G4ParticleHPContAngularPar.cc, line 874)
* G4PHPTEST, read eg in G4ParticleHPEnAngCorrelation::Sample (source\processes\hadronic\models\particle_hp\src\G4ParticleHPEnAngCorrelation.cc, line 143)
* NeutronHPCapture, read eg in G4ParticleHPCapture::ApplyYourself (source\processes\hadronic\models\particle_hp\src\G4ParticleHPCapture.cc, line 103)

The profiles I have run are not the most reproducible (I am using a virtual machine...) and this issue needs to be investigated further.

Comment 1 dennis.herbert.wright 2022-09-16 19:22:57 CEST

This is a known problem for ParticleHP and we are in the process of getting rid of as many getenvs as we can.   I'll have a look at the ones you list and see if they can be removed or replaced.

Comment 2 dennis.herbert.wright 2022-10-07 22:55:33 CEST

Environment variables G4PHPTEST, G4PHPTEST2, NeutronHPCapture and their corresponding getenv()s were no longer used, so they have been removed.