EDM4hep Discussion

Tuesday 9 Feb 2021, 09:00 → 10:00 Europe/Zurich

Zoom

Live Notes

EDM4hep Live Notes
==================

Date: February 9, 2021
Indico: https://indico.cern.ch/event/1001383/

This is a document for taking notes during EDM4hep meetings.

Connected: Tao, Andre, Wenxing, Weidong, Frank, Jiaheng, Teng, Placido, Gerri, Birgit, Benedikt, Graeme, Sanghyun, Thomas, Valentin, Clement

Apologies:

## Introduction and General Points

### Virtual Chep

* **First Drafts next week, Tuesday**
* papers(!) due February 28, 2021
    * Submissions should consist of a paper of 6-10 pages, following the instructions for authors. Paper submission is open until 28 February 2021.
    * https://indico.cern.ch/event/948465/page/21562-instructions-to-submitters

* Contribution:
    * Key4hep overview
    * podio+edm4hep!
        * Created Overleaf and outline

## Fixing Compiler Warnings
* See slides
* PRs
    * https://github.com/AIDASoft/podio/pull/158 (close?)
    * https://github.com/AIDASoft/podio/pull/156 (merge?)
    *
* Unfixable warning for clang and overlength-string in root dictionary
    * Check with newest root version
    * DD4hep ignores the warning
https://github.com/AIDASoft/DD4hep/blob/c179ef49bb51c3ce537b837b335b7293ab59105b/cmake/DD4hepBuild.cmake#L606-L610

* Make a tag after all the warnings are fixed

## Progress and Discussion

## Podio

### Benchmarking
[Thomas] Added some scripts and tools to have almost automatic benchmarking and some results using k4SimDelphes to "generate" data for I/O. Could be made fully automatic with a bit more work and if we want it to be fully automatic.
* https://github.com/tmadlener/podio_benchmarking
* Example results: https://github.com/tmadlener/podio_benchmarking/tree/master/results/k4SimDelphes/ee_Z_bbbar

### Issues/PRs

#### Heap-use-after-free

* https://github.com/AIDASoft/podio/issues/174
* Not a problem in frameworks, but if collections used outside of them
* Deep inside the memory management of podio, so not easy to fix
* Happens more often with clang than with gcc, but could be compiler options.
    * Flagged by address-sanitizer
* Compare with the DD4hep "Handle"s
    * LINK:

#### more fixes to unsigned and shadowed variables
* https://github.com/AIDASoft/podio/pull/158
* https://github.com/AIDASoft/podio/pull/171
    * effc++ warnings not all fixable or not relevant
    * Should check if worth fixing, or downsides
* https://github.com/AIDASoft/podio/issues/170
    * sign vs unsigned
    * using negative values for some special cases (invalid, untracked), could use largest unsigned, or cast to signed when comparing with vectors
    * Maybe better to leave it signed to avoid possible issues with   `max<unsigned> - 1`
    * Use a typedef for the "podIDType"?
    *

#### Multiple Yaml files

* https://github.com/AIDASoft/podio/issues/168
*

#### c++ concepts
* BH: add compile time checks for class behaviours: e.g., movable

#### CollectionIterator does not fully satisfy iterator concept
* https://github.com/AIDASoft/podio/issues/150
* For const collections, would be useful, e.g. using std::find on the collection

#### Idea: True reference collections
* https://github.com/AIDASoft/podio/issues/146

#### issue w/ ROOT and (vectors of) non-copyable collections
* happens in ROOT 6.22
* PM: there is a patch available in LCG repository
    * ROOT team is working on a general solution

#### What are the different branches in the root file?

* Related to use in RDataFrame
* Encode more information in the _relation_ branch names?

#### Multi-Threading

See minutes of https://indico.cern.ch/event/969468/
--> Open issue(s) for further discussion

* Thomas and Benedikt discussing and started to work, nothing to report yet

#### "event class" in podio

* Currently being perceived

### PRs
* https://github.com/AIDASoft/podio/pulls

### Meta Data

#### Usage of "metadata" for user defined data
* need to check if current implementation addresses all use cases
* need test use-cases

### Issues following MetaData Developments

* cannot write out event data previously read from file
    * Issue: https://github.com/AIDASoft/podio/issues/103
    * Test: https://github.com/AIDASoft/podio/pull/102
    * TM: have fix, but break framework core handling of collections

* there seems to be a fix in the Gaudi ROOTWriter in FCC-EDM !?
    * historical reason, fixes and developments should be back ported to PODIO
    * ...

### EventStore

### Schema Evolution

- Version for object descriptions, etc.
- Open issue: https://github.com/AIDASoft/podio/issues/86

### Features

* Subset collections?

## LCIOConverters
* https://github.com/key4hep/k4LCIOReader

* TrackState Covariance Matrix conversion from LCIO
    * https://github.com/key4hep/k4LCIOReader/issues/8
    * Change EDM4hep storage of the covariance matrix
    * What is done in ACTS?
        * Different track parametrisation and time, no easy conversion

## EDM4hep
https://github.com/key4hep/EDM4hep/pulls

### EDM4hep documentation page moved

 

### EDM4hep tools
https://github.com/key4hep/EDM4hep-utils

### Issues

###  Type difference between EDM4hep and LCIO algorithmType (vertex)

* https://github.com/key4hep/EDM4hep/issues/106
* Related to how to store metadata or collection parameters
* Maybe never really used in LCIO
    * Usually store a map of algorithms as collection parameters and refer to the key via the algorithmType (or equivalent)
* --> Keep the int in EDM4hep

### Tracker Hit

* Q: Tracker hit input to tracking algorithms?
* A: In LCIO different traker hits: Planar and Cylindrical using inheritance. Still needs to be adressed how to do this in EDM4hep.
* Q: Is inheritance needed?
* Q: What to use for Driftchambers?
* Open issue:

### Need review of EDM4hepDelphes output

* Output is not stored if no tracks or towers created (?)
    * Allow also other types to be part of the list
    * Allow construction in a more general way (VV)
* Need to assume there is a complete list of reconstructed particles?

* Relations:
    * FCCSW: Issue with more than one RecoParticle pointing to one MCParticle
    * In LCIO to Delphes, conversion happens later than in edm4hep, maybe delphes does de-duplication?
    * TODO: open issue in edm4hep with reproducer (VV)

--> Moving to separate repository

### PRs
https://github.com/key4hep/EDM4hep/pulls/

### Release 1.0

## AOB

### Conditions handling in Belle2
* Benedikt, or Martin Ritter

### Feedback from FCC tutorial for snowmass

* Common question: What are the different branches in the root file?
* ``uproot`` was also used to access the root file
    * Basically re-implemented event store
        * Associations
    * Try to get this into the, e.g., podio repository

### Next meeting:

* February 23, 2021

09:00 → 09:05 Introduction

Speakers: Andre Sailer (CERN), Frank-Dieter Gaede (Deutsches Elektronen-Synchrotron (DE))

EDM4hep Github

Podio Github

09:05 → 09:25 Fixing Compiler Warnings

https://github.com/AIDASoft/podio/pull/170
https://github.com/AIDASoft/podio/pull/171

Speaker: Thomas Madlener (Deutsches Elektronen-Synchrotron (DESY))

podio_warning_fixes.pdf

09:25 → 10:00 Discussion

Speaker: Dr All