ROOT State of the Union

ROOT State of the Union

Fons Rademakers

8th ROOT Users Workshop Saas Fee, 11-14 March 2013

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ROOT - The Beginning

Jan 95: Thinking/writing/rewriting/more thinking Nov 95: Public seminar, presentation of ROOT 0.5 Spring 96: decision to use CINT Jan 97: ROOT version 1.0 Jan 98: ROOT version 2.0 Mar 99: ROOT version 2.21/08 (1st ROOT workshop FNAL) Feb 00: ROOT version 2.23/12 (2nd ROOT workshop CERN) Sep 00: ROOT version 2.25/03 Dec 00: ROOT version 3.00/01 Jun 01: 3rd ROOT Users Workshop at FNAL ... 2005: ROOT finally becoming mainstream at CERN ... Mar 13: 8th ROOT Users Workshop Saas-Fee

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ROOT 1999 - The Core Developers

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ROOT 2013 - The Next Generation

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ROOT - In Numbers of Users

Ever increasing number of users 6800 forum members, 68750 posts, 1300 on mailing list Used by basically all HEP experiments and beyond

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ROOT - In Lines of Code

Compilation time on state of the art MacBookPro 2013: 4’20” (make -j 8) 2007: 20’12” (make -j 2)

As per statsvn metrics

Real MLOCs: 2.75, was 3 with CINT

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As of today 177 PB of LHC data stored in ROOT format

ROOT - In Numbers of Bytes Stored

ALICE: 30PB, ATLAS: 55PB, CMS: 85PB, LHCb: 7PB

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ROOT - In Plots

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New Developments - New Interpreter

Replacing CINT by new cling: correctness, full C++ Cling based on LLVM and clang compiler libraries “New” open source compiler suite, default on OSX and FreeBSD Compiler-grade C++ on its way to C++11 Best diagnostics on the market:

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Cling

Cling released in July 2011 Fully functional C and C++ interpreter Just-in-Time compilation, i.e. always ACLiC Still a few issues to solve, e.g. reloading of code Support multiple interpreter objects (c.f. multi-threaded context) Integration with ROOT close to be finished Interfaces via TCling and TClass Precompiled headers as dictionary, no huge source files See the ROOT 6 presentation https://indico.cern.ch/contributionDisplay.py?contribId=6&confId=217511

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Improvements in I/O

Parallel Tree merging (see next slides) Asynchronous prefetching When enabled, a separate thread will fetch the TTreeCache blocks that are likely to be needed next and the main thread continues the normal data processing Automatic support for more than one TTreeCache per file TTree::SetCacheSize(Long64_t) no longer overrides nor deletes the existing cache. Each cache is completely independent Support for HDFS, Amazon S3, CloudFront and Google Storage Support for LZMA compression

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Parallel Merging

Existing solution: Processing and storing the partial output on each local node and then only at the end of the process, upload to the server and only when all slaves are done, read all files on the server and write to a single output file.

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Parallel Merging

New TFile implementations: TMemFile: a completely in-memory version of TFile. TParallelMergingFile: a TMemFile that on a call to Write will upload its content and reset the TTree objects. New solution: Increase parallelism by having the slaves start uploading the TTree clusters directly to the server which immediately starts saving them in the final output file.

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On-going I/O Development

Continuous review of I/O performance in close collaboration with experiment experts Reimplementation of OptimizeBaskets Explore changing the on-file byte format to little endian Extension of the parallel merger Improvement of thread safety I/O Customization: Nested Objects

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Parallelism for I/O

3 approaches: Parallel Merge via external process Support for one TFile per thread Currently requires meta data (TClass, TStreamerInfo) to be fully build before starting parallel operation. Planning to lifting this restriction in ROOT 6 (requires cling). Internal use of spare cores Ability to read multiple TBranch data in parallel Top level branches can be uncompressed and un-streamed independently. Prefetching of remote file content as a separate thread. Threaded zipping and unzipping of buffers

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ROOT I/O in JavaScript

Provide ROOT file access entirely locally in a browser ROOT files are self describing, the “proof of the pudding...” See the presentation tomorrow morning http://indico.cern.ch/contributionDisplay.py?contribId=5&confId=217511

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Improvements in Histogram Classes

New class for binning multi-dimensional data using a kd tree (TKDTreeBinning) Automatic binning of data every bin will have same entries or same weight (content) Efficient multi-dimensional histogram Can be used to compare MC and data (make bins with MC and compare with the data) Could be used for non-parametric density estimation using kernels

Also new THn class Multidimensional histograms with equal bins For non-sparse multi-dimensional data

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RooFit/RooStats

Framework for statistical calculations Standard tool for producing physics results at LHC Parameter estimation (fitting) Interval estimation (e.g limit results for new particle searches) Discovery significance (quantifying excess of events) Implement several statistical methods (Bayesian, Frequentist, Asymptotic) New tools for model creation and combinations Histfactory: make RooFit models (RooWorkspace) from input histograms See the presentations on Thursday RooFit @ 11:50: http://indico.cern.ch/contributionDisplay.py?contribId=19&confId=217511 RooStats @ 12:10: http://indico.cern.ch/contributionDisplay.py?contribId=23&confId=217511

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New RooStats Features

Classes for computing exclusion limits and discovery significance using the procedure endorsed and agreed by ATLAS and CMS (CLs method for limits) Using both pseudo-experiments or asymptotic formulae Compute observed limits, expected limits and bands

Can be very time consuming, many pseudo-experiment need to be generated and fitted Working on improving performancesMore efficient fitting for multi-parameter problems (improve the new version of Minuit) Investigate parallelization techniques (PROOF, Multi-threads or porting on GPU)

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Example: Higgs Combination

Higgs combination results of ATLAS and CMS Make combined model with several channels and more than 200 parameters RooStats used successfully for producing results: Could use different statistical methods for comparison Required a lot of CPU for fitting each pseudo-experiment Use Grid for submitting all jobs On-going work on improving fitting performances

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New PROOF Features

Increasing number of sites and users deploying PROOF Deployment on ad-hoc PROOF clusters is made easy by PoD http://indico.cern.ch/contributionDisplay.py?contribId=43&confId=217511 The Virtual Analysis Facility - PROOF cluster on a cloud http://indico.cern.ch/contributionDisplay.py?contribId=9&confId=217511 An extensive PROOF bench suite has been developed allowing to test many aspects of PROOF related parameters (network, disk, cpu, etc.) Many stability improvements

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PROOF Developments

Improvement of the connection layer and of the work distribution engine (packetizer) Result merging optimization (see also parallel tree merging in I/O) Improvement of memory management (in merging of results, in sharing common data) Support for dynamic addition of workers Towards a fully-functional multi-master setup Dataset management across clusters Dynamic load-balancing across sub-masters Dynamic re-organization of a set of workers in multi-tier structures to scale up to O(1000) cores Needed for extreme platforms like IBM’s BG/Q

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New MacOS X Native Graphics Backend

Uses native OSX Cocoa and Quartz for graphics Supports easily new features like transparency, gradients and shadows

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Transparency

In parallel to OSX Cocoa and Quartz, transparency is also supported in PDF and TImage outputs.

This provides new possibilities to visualize large data set. As shown on this parallel coordinates plots. These two plots are the same. On top without transparency: useless. Bottom with transparency: all the clusters clearly appear.

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TH2Poly

TH2Poly is a 2D Histogram class, inheriting from TH2, allowing to define polygonal bins of arbitrary shape.

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“Refreshed” Default Graphics Style

The new style “Modern” is a synthesis of different custom styles used by several major experiments.

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New LaTeX Engine - TMathText

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Parallel Geometry Navigation

Enabled via: gGeoManager->SetMaxThreads(N) Fast thread ID retrieval implemented via TLS Each thread works with its own navigator Navigators holding all state-dependent data No locks, no race conditions Stateful data structures migrated to thread data arrays Small overhead by replacing direct access Additional calls to TGeoManager::ThreadId() Partially compensated by percolating stateful data in the calling sequence of some internal methods Excellent scalability See the presentation on Thursday @ 2:20 pm http://indico.cern.ch/contributionDisplay.py?contribId=12&confId=217511

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Eve Event Display

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Enhancing Concurrency

Concurrent tasks TTask+TThread and TTaskManager Concurrency in I/O Read-ahead thread Parallel merger Threaded zipping and unzipping of buffers Concurrency and vectorization in math Introduction of the Vc matrix library Concurrent geometry navigation Thread safe cling Multiple concurrent cling instances

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Tablets and Smart Phones

Currently over 500 million iOS devices, of which 90 millions iPads All of ROOT ported to iOS (little endian, 32-bit, ARM) To cross compile on OSX to iOS native version: ./configure ios To compile on OSX to iOS simulator version: ./configure iossim Android will come later

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Implementing ROOT Graphics on iOS

Ported ROOT’s non-GUI graphics on iOS TVirtualPad interface in ROOT::iOS::Pad using Quartz 2D library Writing ROOT-based native applications for iOS Demo of ROOT’s graphics Browser for ROOT files Future developments Components to support users who want to develop for iOS Port ROOT’s OpenGL code to GL/ES Use HCP (head coupled perspective) technology for event display (Eve) Uses front facing camera Glasses free 3D display

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RootBrowser on the iPad

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Infrastructure

Build using “./configure;make” and now also cmake Subversion (and who knows, git in the future) Static code analyzer Coverity (commercial) New continuous build system Electric Commander (commercial) Incremental and full builds and nightly build snapshots for 14 platforms/configurations New source code convention checker Eclair (commercial, but uses LLVM inside) New documentation system From MS Word to Docbook Drupal based website

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ROOT Roadmap

Current version is v5-34-05 It is an LTS (Long Term Support) version New features will be back ported from the trunk Version v6-00-00 is scheduled for when it is ready It will be Cling based It will not contain anymore CINT/Reflex/Cintex GenReflex will come in 6-02 It might not have Windows support (if not, likely in 6-02) Several “Technology Previews” will be made availble Can be used to start porting v5-34 to v6-00

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Enjoy The Workshop

Conclusions

Users and experiments want an absolutely stable ROOT so their carefully tuned analysis are not disturbed when moving to a new version At the same time we need to extend to new platforms and incorporate new technologies to make life easier for the users and to keep ROOT on the bleeding edge A careful balancing act, but a very exciting one

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One More Thing

The CERN iPhone App

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CERN iPhone App

Developed by members of the ROOT team Application now in public beta People interested in trying it out on their iPhone Send us mail at cern-app@cern.ch for instructions Of course open source: svn co http://root.cern.ch/svn/cern-app/trunk cern-app Need xcode and iOS dev license

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