fads: a (Go-based) FAst Detector Simulation toolkit

HSF, 2015/01/21

fads

fads is a "FAst Detector Simulation" toolkit.

• morally a translation of C++-Delphes into Go
• a testbed for R&D in Go and concurrent frameworks
• uses go-hep/fwk to expose, manage and harness concurrency into the usual HEP event loop (initialize | process-events | finalize)

Code is on github (BSD-3):

github.com/go-hep/fwk

github.com/go-hep/fads

Documentation is served by godoc.org, CI by drone.io:

godoc.org/github.com/go-hep/fwk

godoc.org/github.com/go-hep/fads

go-hep/fads - Installation

As easy as:

$ export GOPATH=$HOME/dev/gocode
$ export PATH=$GOPATH/bin:$PATH

$ go get github.com/go-hep/fads/...

Yes, with the ellipsis at the end, to also install sub-packages.

• go get will recursively download and install all the packages that go-hep/fads depends on. (no Makefile needed)

• you get a statically linked executable in a matter of seconds (even for large projects)

• simplify deployment, distribution

• the speed of development of python with the speed of execution of C++

go-hep/fwk - Concurrency

fwk enables:
- event-level concurrency
- tasks-level concurrency

fwk relies on Go's runtime to properly schedule goroutines.

For sub-task concurrency, users are by construction required to use Go's constructs (goroutines and channels) so everything is consistent and the runtime has the complete picture.

• Note: Go's runtime isn't yet NUMA-aware. A proposal for Go-1.6 (beg-2016) is in the works.

go-hep/fads - real world use case

• translated C++-Delphes' ATLAS data-card into Go
• go-hep/fads-app
• installation:

$ go get github.com/go-hep/fads/cmd/fads-app
$ fads-app -help
Usage: fads-app [options] <hepmc-input-file>

ex:
 $ fads-app -l=INFO -evtmax=-1 ./testdata/hepmc.data

options:
  -cpu-prof=false: enable CPU profiling
  -evtmax=-1: number of events to process
  -l="INFO": log level (DEBUG|INFO|WARN|ERROR)
  -nprocs=0: number of concurrent events to process

go-hep/fads - components

• a HepMC converter
• particle propagator
• calorimeter simulator
• energy rescaler, momentum smearer
• isolation
• b-tagging, tau-tagging
• jet-finder (reimplementation of FastJet in Go: go-hep/fastjet)
• histogram service (from go-hep/fwk)

Caveats:

• no real persistency to speak of (i.e.: JSON, ASCII and Gob)
• jet clustering limited to N^3 (slowest and dumbest scheme of C++-FastJet)

Performances - testbenches

• Linux: Intel(R) Core(TM)2 Duo CPU @ 2.53GHz, 4GB RAM, 2 cores
• MacOSX-10.6: Intel(R) Xeon(R) CPU @ 2.27GHz, 172GB RAM, 16 cores
• Linux: Intel(R) Xeon(R) CPU E5-2660 v2 @ 2.20GHz, 40 cores

Linux (40 cores) testbench: memory

Linux (40 cores) testbench: event throughput

go-hep

go-hep project

A set of pure-Go or bindings to HEP libraries

• go-hep/fads: fast detector simulation toolkit
• go-hep/fastjet: jet clustering algorithms (WIP)
• go-hep/fmom: 4-vectors
• go-hep/fwk: concurrent framework
• go-hep/hbook: histograms and n-tuples (WIP)
• go-hep/hplot: interactive plotting (WIP)
• go-hep/hepmc: HepMC in Go (EDM + I/O)

go-hep + astrogo project (cont'd)

• go-hep/hepevt: HEPEVT bindings
• go-hep/heppdt: HEP particle data table
• go-hep/lhef: Les Houches Event File format

• go-hep/croot: bindings to a subset of ROOT I/O
• go-hep/rio: go-hep record oriented I/O
• go-hep/sio: LCIO I/O
• go-hep/slha: SUSY Les Houches Accord I/O

• astrogo/cfitsio: bindings to FITSIO
• astrogo/fitsio: pure Go I/O for FITS files
• astrogo/vo/votable: I/O for VOTable

• sbinet/hdf5: bindings to HDF5

go-hep & HSF

Most of development workflow already addressed (doc, CI, DVCS)

HSF could provide (from go-hep POV):

• wider audience (users, developers)
• test machines/architectures
• storage area for input data (for tests) and/or (binary) releases
• agreement on cross-language interoperability (file formats, data layout) in a non pure- C++ environment

Thank you