ROOT Version 6.20 Release Notes

Introduction

ROOT version 6.20/00 was released on February 26, 2020.

For more information, see:

http://root.cern

The following people have contributed to this new version:

Kim Albertsson, CERN/ATLAS,
Guilherme Amadio, CERN/SFT,
Bertrand Bellenot, CERN/SFT,
Iliana Betsou, CERN/SFT,
Jakob Blomer, CERN/SFT,
Brian Bockelman, Nebraska,
Rene Brun, CERN/SFT,
Philippe Canal, FNAL,
Javier Cervantes Villanueva, CERN/SFT,
Olivier Couet, CERN/SFT,
Alexandra Dobrescu, CERN/SFT,
Giulio Eulisse, CERN/ALICE,
Johannes Hentrich,
Massimiliano Galli, CERN/SFT and Unibo,
Gerri Ganis, CERN/SFT,
Andrei Gheata, CERN/SFT,
Hadrien Grasland, CNRS,
Enrico Guiraud, CERN/SFT,
Stephan Hageboeck, CERN/SFT,
Desislava Kalaydjieva, CERN/SFT,
Jan Knedlik, GSI,
Philip Leindecker, CERN/SFT,
Sergey Linev, GSI,
Alfonso Luis Castano Marin, UMU,
Pere Mato, CERN/SFT,
Emmanouil Michalainas, AUTh,
Lorenzo Moneta, CERN/SFT,
Alja Mrak-Tadel, UCSD/CMS,
Axel Naumann, CERN/SFT,
Joana Niermann, CERN-SFT,
Vincenzo Eduardo Padulano, Bicocca/SFT,
Danilo Piparo, CERN/SFT,
Fons Rademakers, CERN/SFT,
Otto Schaile, Uni-Muenchen,
Henry Schreiner, Princeton,
Oksana Shadura, Nebraska,
Simon Spies, GSI,
Matevz Tadel, UCSD/CMS,
Yuka Takahashi, Princeton and CERN/SFT,
Enric Tejedor Saavedra, CERN/SFT,
Vassil Vassilev, Princeton/CMS,
Wouter Verkerke, NIKHEF/ATLAS,
Stefan Wunsch, CERN/SFT,
Luca Zampieri, CERN-SFT,
Zhe Zhang, Nebraska

General

Splash screen

The venerable splash screen is now disabled by default to make ROOT’s startup faster. Many users already use root -l to start ROOT, but this also hides the useful text banner with version information along with the splash screen. With this new default, starting up ROOT as just root will show only the text banner instead of the splash screen. The splash screen can still be seen with root -a or in TBrowser by opening Browser Help → About ROOT.

Deprecation and Removal

• rootcling flags -cint, -gccxml, -p, -r and -c have no effect and will be removed in a future release. Please remove them from the rootcling invocations.
• rootcling legacy cint flags +P, +V and +STUB have no effect and will be removed in a future release. Please remove them from the rootcling invocations.
• genreflex flag --deep has no effect and will be removed in a future release. Please remove it from the genreflex invocation.
• rootcling warns if it sees and unrecognized flag (usually coming from the CXXFLAGS of the build system). Please remove them from the invocation because the warning will become a hard error in the next releases.
• The empty headers Gtypes.h and Htypes.h are deprecated. Please include Rtypes.h

Core Libraries

• Speed-up startup, in particular in case of no or poor network accesibility, by avoiding a network access that was used as input to generate a globally unique ID for the current process.
• This network access is replaced by a passive scan of the network interface. This reduces somewhat the uniqueness of the unique ID as the IP address is no longer guaranteed by the DNS server to be unique. Note that this was already the case when the network access (used to look up the hostname and its IP address) failed.

I/O Libraries

• TFile: A new bit TFile::kReproducible was introduced. It can be enabled by specifying the "reproducible" url option when creating the file:

  TFile *f = TFile::Open("name.root?reproducible","RECREATE","File title");

  Unlike regular TFiles, the content of such file has reproducible binary content when writing exactly same data. This achieved by writing pre-defined values for creation and modification date of TKey/TDirectory objects and null value for TUUID objects inside TFile. As drawback, TRef objects stored in such file cannot be read correctly.

• Significantly improved the scaling of hadd tear-down/cleanup-phase in the presence of large number histograms and in the presence of large number of directories.
• TMemFile: Apply customization of minimal block size also to the first block.
• Add renaming rule for instances of the math classes from genvector and smatrix to instance for one floating point type (float, double, Double32_t, Float16_t) to instances for any other floating point type.
• Corrected the application of I/O customization rules when the target classes contained typedefs (in particular Double32_t)
• Prevent splitting of objects when a Streamer Function was explicitly attached to their TClass.
• In hadd fix verbose level arg parsing
• Allow user to change the type of the content of a TClonesArray.

• Avoid deleted memory access in MakeProject and in handling of I/O customization rules.

Compression algorithms

• Added a new compression algorithm ZSTD [https://github.com/facebook/zstd.git], a dictionary-type algorithm (LZ77) with large search window and fast implementations of entropy coding stage, using either very fast Finite State Entropy (tANS) or Huffman coding. ZSTD offers a better compression ratio and faster decompression speed comparing to ZLIB. Its decompression speed is 2x faster then ZLIB and at least 6x faster comparing to LZMA. ZSTD provides a wide range of compression levels, and after evaluation we recommend to use for your purposes compression level 5 (or 6). To use ZSTD please use next settings:

   root [1] _file0->SetCompressionAlgorithm(ROOT::RCompressionSetting::EAlgorithm::kZSTD)
   root [2] _file0->SetCompressionLevel(ROOT::RCompressionSetting::ELevel::kDefaultZSTD)

  or

  root [3] _file0->SetCompressionSettings(505)

  or

  root [3] _file0->SetCompressionSettings(ROOT::RCompressionSetting::EDefaults::kUseGeneralPurpose)

TTree Libraries

• Prevent a situation in TTreeFormula when stale cached information was re-used.
• Prevent a noticeable memory leak when reading uncompressed TTree.

RDataFrame

• Improved CSV data source
  • Support for 1.0e+10 syntax for type inference of double columns
  • Empty lines are now skipped

Histogram Libraries

• Allow reading v5 TF1 that were stored memberwise in a TClonesArray.
• Make RHist bin iteration order consistent with that of THx.
• Add RCoordArray constructor from std::array.
• Remove thread-unsafe accessors of RHistConcurrentFill.
• Fix Flush logic of buffered RHist wrappers.
• New class TGraphMultiErrors: A TGraph with asymmetric error bars and multiple y error dimensions (author: Simon Spies).

Math Libraries

• ROOT::Math::KahanSum can use SIMD instructions for faster accumulation

RooFit Libraries

• Documentation Many improvements to the doxygen documentation of RooFit classes.

• Automatic legends for RooPlot RooPlot now supports BuildLegend as a good starting point for a legend.

• Short prefits In unbinned fits that take long, good starting values for parameters can be found by running a short prefit before the final fit. Passing PrefitDataFraction(0.1) to fitTo() will e.g. run a prefit on 1% of the data.

• Iterating over categories Category classes deriving from RooAbsCategory, e.g. RooCategory now support “natural” iterating using range-based for loops in C++ or Python loops:

  import ROOT
  cat = ROOT.RooCategory("cat", "cat")
  cat.defineType("1Lep", 1)
  cat.defineType("2Lep", 2)
  for state in cat:
    print(state.getVal(), state.GetName())
  
  (1, '1Lep')
  (2, '2Lep')

• Asymptotically correct parameter uncertainties Added computation of asymptotically correct parameter uncertainties in likelihood fits with event weights. See arXiv 1911.01303 and rf611_weightedfits.C.

• Barlow-Beeston tutorial The tutorial rf709_BarlowBeeston.C has been added to RooFit to demonstrate how to incorporate Monte Carlo statistics as systematic uncertainties into a fit. It demonstrates both the “full” and the “light” method.

• RooFitMore for GSL All parts of RooFit that use the GSL (PDFs and integrators) have been moved into the library RooFitMore. It gets enabled automatically with the MathMore library (-Dmathmore=ON, default). Note that -lRooFitMore might now be required when linking against RooFit.

Fast function evaluation and vectorisation

A BatchMode for faster unbinned fits has been added. By loading data more efficiently, unbinned likelihood computations can run about 3x faster if the PDFs support it. To enable it, use

pdf.fitTo(data, RooFit::BatchMode());

Most unbinned PDFs that are shipped with RooFit have been updated to support this mode.

In addition, if ROOT is compiled for a specific architecture, SIMD instructions can be used in PDF computations. This requires ROOT to be compiled with -march=native or e.g. -mavx2 if the hardware supports it. For maximal performance, ROOT should also be configured with -Dvdt=ON. VDT is a library of fast math functions, which will automatically be used in RooFit when available. Depending on the compiler, on the instruction set supported by the CPU and on what kind of PDFs are used, PDF evaluations will speed up 5x to 16x. For details see CHEP 2019.

New RooFormulaVar / RooGenericPdf

RooFormula has been updated to use ROOT’s TFormula. This means that expressions passed to RooFormulaVar / RooGenericPdf are compiled with -O2 optimisation level before they are evaluated. For complicated functions, this might improve the speed of the computation. Further, functions that are known to the interpreter can be used in the expression passed to a PDF. The following macro e.g. prints the expected result 5.4:

  double func(double x, double a) {
    return a*x*x + 1.;
  }

  void testRooFormulaWithClingFunction() {
    RooRealVar x("x", "x", 2, -10, 10);
    RooRealVar a("a", "a", 1.1, -10, 10);

    RooGenericPdf pdf("pdfWithExternalFunc", "func(x, a)", {a, x});
    std::cout << pdf.getVal() << std::endl;
  }

New PDFs added to RooFit

• RooHypatia2, featuring a hyperbolic, Crystal-ball-like core and two adjustable tails.
• RooWrapperPdf, a class that can convert any function (= not normalised) into a PDF by integrating and normalising it.

RooStats / HistFactory

• To facilitate plotting of pre-fit model uncertainties, gamma parameters now have reasonable pre-fit uncertainties.
• RooStats global config switches are now all accessible in one place, RooStats::GetGlobalRooStatsConfig().
• Tools like ToyMCSampler and HypoTestInverter have been stabilised and better validate their inputs to prevent infinite loops or crashes.
• SPlot now accepts additional arguments for the internal fitting step to e.g. add fit ranges or constraint flags.

2D Graphics Libraries

• Provide support of NDC coordinates for TArrow.
• Fix interactive movement of TLine/TArrow objects when NDC coordinates are used.
• Provide TGraph::MovePoints() method.
• New options RXand RY for TMultiGraph in order to draw reverse axis along X and Y.
• Combined with the option “Z” the option “CJUST” allows to draw the color palette with axis labels justified on the color boundaries (implemented by Otto Schaile).
• The TCanvas Event Status Bar now displays the date and time when the mouse cursor is moved over a time axis (implemented by Otto Schaile).
• Negative values were not painted with option “TEXT” for TH2Poly.
• The Z title was not properly set in TEfficiency.
• Implement TImage:ls()
• TGraph2D: X Y and Z titles were not saved by SavePrimitive.
• In some cases vertical hatches drawn by TPad::PaintHatches disappeared.
• Save the X and Y axis limits in TMultiGraph::SavePrimitive.
• Some markers did not match between PDF and PNG.
• The MaxDigits attribute was not imported from TAxis to TGaxis.

3D Graphics Libraries

Technology preview release of EVE-7: a server-client implementation of TEve for ROOT-7.

• Visualization of simple physics objects
  • points, tracks, jets, line-sets, vertex ellipsoid, and generic geometrical shapes
• Support for handling of physics object collections – a container of objects of a given class
  • physics items can be represented in all views:
    • graphical views of any type (3D, RhoZ and RhoPhi)
    • table views with possibility to edit content dynamically
  • coherent selection of collection items across all instantiated views
• To try it out:
  • build with -DCMAKE_CXX_STANDARD="17" -Dhttp="ON" -Droot7="ON"
  • see examples in tutorials/eve7

Language Bindings

Jupyter Notebook Integration

• When starting Jupyter server with root --notebook arg1 arg2 ..., extra arguments can be provided. All these arguments delivered as is to jupyter executable and can be used for configuration. Like server binding to specific host root --notebook --ip=hostname
• Remove c.NotebookApp.ip = '*' from default jupyter config. One has to provide ip address for server binding using root --notebook --ip=<hostaddr> arguments
• Now Jupyter Notebooks will use JSROOT provided with ROOT installation. This allows to use notebooks without internet connection (offline).

JavaScript ROOT

• Provide monitoring capabilities for TGeoManager object. Now geomtry with some tracks can be displayed and updated in web browser, using THttpServer monitoring capability like histogram objects.
• JSROOT graphics are now supported in the JupyterLab interface. They are activated in the same way as in the classic Jupyter, i.e. by typing at the beginning of a notebook cell:

%jsroot on

Tutorials

• Add the “Legacy” category collecting the old tutorials which do not represent any more best practices

Class Reference Guide

• Images in tutorials can now be displayed à JavaScript thanks to the (js) option added next to the directive \macro_image
• As the tutorial palettes.C is often hit when searching the keyword palette in the reference guide, a direct link from this example to the full list of predefined palettes given in TColor has been added.
• Revisited the TSpectrum2 documentation. All the static images have been replaced by macros generating images at reference guide build time. These macros have been added in the tutorial section of the reference guide.

• The Reference Guide can now be accessed directly from the ROOT prompt thanks to a great extension (implemented by Desislava Kalaydjieva) of the .help command. For example to access the Reference Guide for TTree it is enough to type:

  root[0] .help TTree

  To open the reference guide for a function/member:

  root[0] .help TTree::Draw

• Change the layout of the ROOT reference.

Build, Configuration and Testing Infrastructure

• Option python was renamed to pyroot. The option spelled python is a deprecated alias for pyroot.
• Make MLP optional via the -Dmlp={OFF,ON} switch for CMake
• Make Spectrum optional via the -Dspectrum={OFF,ON} switch for CMake
• ROOT now fails to configure when any package is missing when -Dfail-on-missing=ON is passed to CMake
• The -Dall=ON now switches the default value of all optional packages to ON
• The options astiff, cling, pch, thread, and explicitlink have been removed and are now ignored. They either had no effect (their value was not being used in the build system), or could not be disabled (like cling and explicitlink).
• ROOT library targets now export which C++ standard they were built with via the target compile features cxx_std_11, cxx_std_14, and cxx_std_17.
• The file RootNewMacros.cmake has been renamed to RootMacros.cmake. Including the old file by name is deprecated and will generate a warning. Including RootMacros.cmake is not necessary, as now it is already included when calling find_package(ROOT). If you still need to inherit ROOT’s compile options, however, you may use include(${ROOT_USE_FILE}) as before.
• ROOT’s internal CMake modules (e.g. CheckCompiler.cmake, SetUpLinux.cmake, etc) are no longer installed with make install. Only the necessary files by dependent projects are installed by default now, and they are installed directly into the cmake/ directory, not cmake/modules/ as before.
• The macro ROOT_GENERATE_DICTIONARY() can now attach the generated source file directly to a library target by using the option MODULE <library>, where <library> is an existing library target. This allows the dictionary to inherit target properties such as compile options and include directories from the library target, even when they are added after the call to ROOT_GENERATE_DICTIONARY().
• The macros REFLEX_GENERATE_DICTIONARY() and ROOT_GENERATE_DICTIONARY() can now have custom extra dependencies added with the options DEPENDS and EXTRA_DEPENDENCIES, respectively.
• CMake build types DEBUGFULL, OPTIMIZED, and PROFILE have been removed. They were not in use and did not work in all platforms.
• The default build type is now empty to ensure that CXXFLAGS set by the user are always respected. If no flags are set, then the build type defaults to release.
• The version of Python that ROOT has been built with is now exported in the CMake variable ${ROOT_PYTHON_VERSION}, available after calling find_package(ROOT).

The following builtins have been updated:

• CFITSIO 3.450
• FFTW3 3.3.8
• GSL 2.5
• Intel TBB 2019 U9
• PCRE 8.43
• OpenSSL 1.0.2s
• Vdt 0.4.3
• VecCore 0.6.0
• XRootD 4.10.0
• Zstd 1.4.0
• LZ4 1.9.2

PyROOT

Current PyROOT

• Several changes for forward compatibility with experimental PyROOT and new Cppyy have been added:
  • Template instantiation can be done with square brackets. The parenthesis syntax is deprecated.

  my_templated_function['int','double']()  # new syntax
  my_templated_function('int','double')()  # old sytax, throws a deprecation warning

  • When converting None to a null pointer in C++, a deprecation warning is issued.
  • When using buffer.SetSize a deprecation warning is issued, the forward compatible alternative is buffer.reshape.
  • When using ROOT.Long or ROOT.Double, a deprecation warning is issued in favour of their equivalent ctypes types (c_long, c_int, c_double)
  • Added the forward compatible names as_cobject and bind_object for AsCObject and BindObject, respectively.
  • nullptr is also accessible as cppyy.nullptr, not only as cppyy.gbl.nullptr.
  • Pythonization functions (e.g. add_pythonization) are accessible via cppyy.py.
  • Some attributes of Python proxies have been added with the name they have in the new Cppyy (__creates__, __mempolicy__, __release_gil__ for function proxies, __smartptr__ for object proxies).
• The support for enums (both scoped and non-scoped) was improved. Now, when creating an enum from Python, its underlying type is obtained by PyROOT.
• Added support for non-ASCII Python strings (e.g. UTF-8) to std::string and C string.
• Added converters from bytes to std::string and to C string.
• Added compatibility of STL iterators with GCC9.
• Added support for templated methods with reference parameters.
• Introduced two teardown modes: soft and hard. The soft one only clears the proxied objects, while the hard one also shuts down the interpreter.

Experimental PyROOT

• MultiPython: build and install PyROOT with multiple Python versions.
  • Build:

  cmake -DPYTHON_EXECUTABLE=/path/to/first/Python/installation /path/to/ROOT/source
  cmake --build .
  cmake -DPYTHON_EXECUTABLE=/path/to/second/Python/installation /path/to/ROOT/source
  cmake --build .
  ( ... )

  • Source a specific built version (last one picked as default):

  ROOT_PYTHON_VERSION=X.Y source /path/to/bin/thisroot.sh

  • PyROOT installation directory can be customized:

  cmake -DCMAKE_INSTALL_PYROOTDIR=/path/to/PyROOT/install/dir /path/to/ROOT/source
  cmake --build .
  make install

• Updated cppyy packages to the following versions:
  • cppyy: cppyy-1.5.3
  • cppyy_backend: clingwrapper-1.10.3
  • CPyCppyy: CPyCppyy-1.9.3
• Introduced two teardown modes: soft and hard. The soft one only clears the proxied objects, while the hard one also shuts down the interpreter.
• A few changes for backward compatibility with current PyROOT have been added:
  • Added MakeNullPointer(klass) as bind_object(0,klass)
  • Provided BindObject and AsCObject
• ROOT.Long and ROOT.Double are no longer in the API of PyROOT, since new Cppyy requires to use their equivalent ctypes types (c_long, c_int, c_double).
• Added TPython.
• Added support for from ROOT import * in Python2 (only).

TMVA

• Introduce RTensor class, a container for multi-dimensional arrays similar to NumPy arrays
• Add AsTensor to convert data from a RDataFrame to a RTensor
• Introduce a fast tree inference engine able to generate optimized inference code using just-in-time compilation of model parameters
• New experimental TMVA reader interface RReader following a sklearn-like API in C++ and Python
• New experimental interface for preprocessing methods (RStandardScaler)
• New GPU implmentation of convolutional layer using the cuDNN library. It is used as default when the cuDNN library is installed in the system

Bugs and Issues fixed in this release

• [ROOT-9817] Batch evaluations in RooxxxPDFs
• [ROOT-9818] Generic batchEvaluate in RooAbsPdf
• [ROOT-9819] batchEvaluate functions for heavily used PDFs
• [ROOT-9882] Use VDT Math functions
• [ROOT-10048] [DF] Improve error handling in Profile1D and Profile2D
• [ROOT-10128] Fix GCC 9 warnings in core libraries
• [ROOT-10129] Fix GCC 9 warnings in cling/metacling
• [ROOT-10134] Fix GCC 9 warnings in I/O libraries
• [ROOT-10137] Fix GCC 9 warnings in histogram libraries
• [ROOT-10307] Implementation of Hypatia PDF
• [ROOT-4756] RooFit: Fitting in multiple disjoint ranges broken
• [ROOT-5976] tutorials/roofit/rf313_paramranges.C division by zero at RooIntegrator1D.cxx:285
• [ROOT-6008] RooAddPdf::_coefCache does not check bounds
• [ROOT-6260] data looses their name when copying a RooWorkspace
• [ROOT-6988] Make enum’s underlying type available
• [ROOT-7139] Seg Fault in TH2Poly -> TH1::Divide
• [ROOT-7240] namespace of class enum from dictionaries
• [ROOT-7520] Segmentation fault when loading a RooLinearVar from a RooWorkspace
• [ROOT-7836] running roottest via ctest popules ~/.root_hist
• [ROOT-8291] RooFormulaVar in RooWorkspace after saving to ROOT file
• [ROOT-8412] RMS calculation with negative bin content
• [ROOT-8522] RooDataHist’s assignment operator seems to be broken
• [ROOT-8932] Impossible to plot multiple filled PDFs using RooFit::AddTo()
• [ROOT-8936] ROOT’s dictionary can get “confused” when asking for it with the “wrong name”
• [ROOT-9112] rootcing wildcarding should ignore private/protected inner classes
• [ROOT-9385] CMake unexpected behavior with -Dfail-on-missing=ON
• [ROOT-9449] cmake -Dexplicitlink=OFF configuration does not compile
• [ROOT-9647] Cannot configure with -Droottest=ON when using a release tarball
• [ROOT-9661] Cannot configure ROOT with builtin_clang=OFF
• [ROOT-9678] Builtin TBB fails to compile on Mac OS when CUDA toolkit is installed
• [ROOT-9708] Automatic first checkout of roottest fails if not on master
• [ROOT-9741] ROOT fails to read objects derived from TH2Poly
• [ROOT-9755] Linker error - Missing symbols from libcurl in fitsio package
• [ROOT-9758] Installed ROOT cannot find its libraries
• [ROOT-9828] ROOT installs internal CMake modules
• [ROOT-9842] Build Error: fatal error: cyclic dependency in module ROOTGraphicsPrimitives
• [ROOT-9965] Segfault with TEve on ROOT 6.16.00 from LCG 95
• [ROOT-10031] [Exp PyROOT] Cppyy error when accessing typedef in a struct
• [ROOT-10050] [Exp PyROOT] TPython::LoadMacro is broken in Cppyy
• [ROOT-10094] ROOT Cross-hatch for TGraph does not fill completely
• [ROOT-10096] [Exp PyROOT] Lack of memory management for TFile-owned objects
• [ROOT-10144] TFormula v5 reads/writes after array
• [ROOT-10188] RooDataSets with large weight array cannot be serialised
• [ROOT-10193] Using an undeclared identifier makes ROOT crash
• [ROOT-10194] using ofstream in the prompt makes ROOT crash
• [ROOT-10197] CUDA Builds broken after adding dependency in TMVA to Vecops
• [ROOT-10211] GCC 9: TStyle has user defined copy constructor, but no operator=
• [ROOT-10216] TFile::MakeProject severely broken
• [ROOT-10221] cling::Value broken if placement-new constructor fails
• [ROOT-10222] PyROOT converts Python 3 str → const char* and not bytes → const char*
• [ROOT-10224] Crash in opening TFile
• [ROOT-10227] [TreeProcMT] Last cluster in processed TTree is dropped under specific circumstances
• [ROOT-10228] TCanvas.SaveAs saves png files only in batch mode
• [ROOT-10241] Header TBulkBranchRead.hxx recursively includes TBranch.h
• [ROOT-10242] RooMCStudy crashes when requesting pulls for parameters that don’t have pulls
• [ROOT-10244] Nested std::pair written with 6.14/GCC 8.2 not readable with 6.18/GCC 8.3
• [ROOT-10245] Template proxy error when invoking reset on std::shared_ptr
• [ROOT-10250] roottest picks up installed ROOT instead of the ROOT being built/tested
• [ROOT-10254] FoldFileOutput breaks output log
• [ROOT-10255] TCutG copy constructor is wrong
• [ROOT-10257] ROOT does not respect users’ CXXFLAGS
• [ROOT-10259] RooDataSet::add has side effects on event weight error
• [ROOT-10280] TH2Poly::Add wrongly adds bin content
• [ROOT-10290] MacOS: TRint doesn’t catch exceptions
• [ROOT-10292] PYROOT: “TypeError: can not resolve method template call”
• [ROOT-10293] Missing CMake information about Python version
• [ROOT-10295] [PyROOT experimental] Segfault at destruction time of a TFile/TTree combination
• [ROOT-10297] Crash in RooDataHist::sum
• [ROOT-10305] Leading underscore in branch name causes a crash
• [ROOT-10306] Failure with std::unique_ptr in STL container
• [ROOT-10313] [RCsvDS] Double column deduced as std::string
• [ROOT-10323] Segfault in PyROOT at exit
• [ROOT-10331] ROOT behavior changes when build with Debug and Release
• [ROOT-10333] seg fault with std::shared_ptr
• [ROOT-10334] TFile::GetBestBuffer casting to Int_t Overflows
• [ROOT-10337] TClassEdit::ResolveTypedef leaves a spurious “std”
• [ROOT-10339] First of the tree tutorials crashes when trying to histogram a leaf
• [ROOT-10340] Segmentation violation associated with TSocket::Recv
• [ROOT-10343] illegal memory overwrite in TMemberInspector::TParentBuf::Append
• [ROOT-10344] stack overflow in rootcling on anonymous union
• [ROOT-10358] RooRealVar’s assignment operator is broken
• [ROOT-10360] TFitResult->Scan() crashes when multi-threading is enabled
• [ROOT-10367] RooFormulaVar with categories crash when plotted
• [ROOT-10369] Inverted logic in assert in TEveVectorT on Windows
• [ROOT-10370] Builtin CFITSIO has several security vulnerabilities
• [ROOT-10375] V523 The then statement is equivalent to the else statement. MethodMLP.cxx 423
• [ROOT-10391] Marker 29 looks different in png and pdf output
• [ROOT-10411] RooFormula doesn’t compile when arguments are renamed
• [ROOT-10413] RooDataSet Import Tree Branch with long name
• [ROOT-10426] Crash in recursive compilation / new autoloading
• [ROOT-10449] Measurement::PrintXML() crashes on 6.18+
• [ROOT-10452] ROOT configured with -Dgnuinstall=ON doesn’t work when installed with make install
• [ROOT-10469] CMS: pyroot teardown issue
• [ROOT-10473] RooAbsData::convertToTreeStore forgets event weights
• [ROOT-10474] Cannot iterate on std::map in Python using gcc9 builds
• [ROOT-10475] Ownership of TTree is shared between RooFit and file after writing a RooDataSet
• [ROOT-10481] TBinomialEfficiencyFitter::Fit ignores the parameter limits
• [ROOT-10491] AsNumpy fails with Boolean columns
• [ROOT-10495] PyArrayObject redefined in TMVA/PyMethodBase.h with different type
• [ROOT-10504] Mixed dictionary / autoparse fails Cling/Clang assertion
• [ROOT-10511] clang assertion in debug builds with Python
• [ROOT-10512] Implicit conversion from string_view to TString breaks existing code
• [ROOT-10517] RooFit::CutRange is buggy with multiple range
• [ROOT-10518] chi2FitTo and fitTo are not working properly with multiple ranges
• [ROOT-10526] Segfault in [some] std::vector<T, custom_alloc<T>> I/O
• [ROOT-10528] The TClass for HepMC::GenVertex is being unloaded when in state 3
• [ROOT-10552] TStreamerInfo removed from the file when new object is written
• [ROOT-10557] Wrong results when using TTree::Draw/Scan on specific entries of vectors of vectors
• [ROOT-10574] TClassEdit::GetNormalizedName is wrong on OSX
• [ROOT-10167] root-config --python-version returns an empty string
• [ROOT-8777] Making it possible to turn off the stdout message in RooMCStudy
• [ROOT-9332] TFileMerger/hadd using restricted sources list on recursive call ?
• [ROOT-8646] Roo(Stats,Fit) - use new TFormula
• [ROOT-10127] Fix GCC 9 Warnings
• [ROOT-7549] Can’t make CMake dictionary generation functional with Ninja
• [ROOT-8575] ROOT_GENERATE_DICTIONARY interface for CMake Usage Requirements/Generator Expressions
• [ROOT-10022] [DF] Add support for TBranchObjects (e.g. branches containing TH2F)
• [ROOT-10103] tutorial nbviewer links point to root.cern.ch, not root.cern
• [ROOT-10164] Replace v5 TFormula in RooFit by JITted TFormula
• [ROOT-10173] Re-enable RooJohnson unit test
• [ROOT-10230] TPythia8: Add option to disable banner in constructor
• [ROOT-10268] PyROOT Allow to pickle the numpy array wrapper used in AsNumpy
• [ROOT-10299] Info symbols found twice in Pythia and ROOT
• [ROOT-10310] Reverse axis drawing options RX and RY should be also allowed in TMultiGraph

Release 6.20/02

Released on March 15, 2020

Bugs and Issues fixed in this release

• [ROOT-10576] - Error getting list of methods of std in cxx17
• [ROOT-10595] - Fix TH1::KolmogorovTest when using option X
• [ROOT-10605] - wrong slice in plotting simultaneous pdf built with RooSimWSTool
• [ROOT-10613] - Configuration does not fail when fail-on-missing is ON and cudnn is not found
• Build failures due to missing CuDNN.
• Do not overwrite existing LD_LIBRARY_PATH.
• Deprecate “python” CMake option: use “pyroot” instead.
• Protect multi-thread access to TSystem::fHelper.
• Fix plotting slices of RooSimultaneous.
• Fix the copying of the trained mu and variance parameters in the BatchNormLayer.
• Fix in MethodPyKeras for the different API in version 2.
• [DF] Throw in case of Snapshot w/ IMT + “UPDATE” mode
• [clingutils] Handle non-defaulted template arg after defaulted arg:
• Move RRawFile from Experimental::Detail to Detail
• [DF] use RRawFile in SQlite data source, making Davix a plugin.
• [CMake] Fix ‘Numpy not found’ bug.

Release 6.20/04

Released on April 1, 2020

Bugs and Issues fixed in this release

• [ROOT-9556] - [DF] Users might silently get wrong results when they process two trees as friends, one of which has been produced by a multi-thread Snapshot of the other
• [ROOT-10624] - [Graphics][JSROOT] Broken histogram fill color with %jsroot on
• [ROOT-10630] - Failed to run python code: copy_string=history.history.keys()[0]
• [ROOT-10631] - Glew includes are not properly found on Mac OS X Catalina
• [ROOT-10647] - Missing implementation of “section” in RooArgSet::writeToStream
• Fix build configuration for CUDA in non-standard directory.

Release 6.20/06

Released on June 10, 2020

Bugs and Issues fixed in this release

• [ROOT-7435] - Histogram titles with latex appear tiny in TCanvas if gROOT.IsBatch() is True
• [ROOT-7986] - Severe memory leak reading RooFitResult and HypoTestInverterResult from disk
• [ROOT-9535] - Unexpected crash when cloning TH2 histogram
• [ROOT-10178] - TTreeProcessorMT can’t deal with trees with different names in the same TChain
• [ROOT-10209] - ROOT 6.18/00 does not compile with CUDA available in C++17 mode
• [ROOT-10626] - Build Fails when python3-numpy not present (Fedora 31)
• [ROOT-10648] - Occasional streamer type mismatch in multi-thread TTree writing
• [ROOT-10658] - wrong -I flags provided for dictionary compilation
• [ROOT-10663] - ROOT dictionary for ATLAS persistent class can’t load correctly
• [ROOT-10668] - RooFit with Asymptotically Correct approach will segfault if RooRealVar Name != Title
• [ROOT-10670] - hesse does not know which minimizer to use
• [ROOT-10673] - TPad::logX broken for histograms with Sumw2 errors
• [ROOT-10676] - Constructing a RooDataSet from TTree with cuts causes warnings
• [ROOT-10682] - Some histograms with custom axes and error bars not displayed on log-log canvas
• [ROOT-10696] - TDirectory::GetObject() with wrong type leaks memory
• [ROOT-10712] - Failing template instantiation during tear down.
• [ROOT-10719] - Some TH1-s Display Incorrectly in root 6.20.04
• [ROOT-10725] - cmake fails to detect python’s “Development” component
• [ROOT-10732] - hadd broken
• [ROOT-10734] - pymva tutorials not disable when pymva not available
• [ROOT-10754] - [cling] Miscompilation with make_shared/shared_ptr
• [ROOT-10766] - Missing overload in LHCb’s FuncOps__::__le__
• [ROOT-10774] - rootbrowse freezes after startup
• [ROOT-10777] - Cannot py-import Gaudi: assert “partial specialization scope specifier in SFINAE context”
• [ROOT-10784] - Mistake in what is reported in documentation
• [ROOT-10792] - [DF] Snapshot of TClonesArrays read via TTreeReaderArray is broken
• [ROOT-10798] - ROOT 6.20/02 can’t generate a dictionary for ATLAS’s EventLoop package
• [ROOT-10804] - assertion in clang::Sema::LookupSpecialMember
• [ROOT-10810] - Segmentation fault in pickling of weighted RooFit datasets
• [ROOT-10822] - [DF] RVecs of non-split branches can read from invalid addresses

Release 6.20/08

Released on August 18, 2020

TTree

• TTree::GetBranch has been updated to execute its search trough the set of branches breadth first instead of depth first. In some cases this changes the branch that is returned. For example with:

    struct FloatInt {
       float f;
       int x;
    };

and

   int x = 1;
   FloatInt s{2.1, 3};
   TTree t("t", "t");
   t.Branch("i", &i); // Create a top level branch named "i" and a sub-branch name "x"
   t.Branch("x", &x);

the old version of t.GetBranch("x") was return the i.x sub-branch while the new version return the x top level branch.

• TTree::GetBranch was also upgraded to properly handle being give a full branch name. In prior version, with the example above, GetBranch("i.x") would return nullptr. With the new version it returns the address of the branch i.x.

• TChain now properly carries from TTree to TTree, each TBranch MakeClass (also known as DecomposedObj[ect] mode, if it was set (implicitly or explicitly).

• TTree::SetBranchAddress and TChain::SetBranchAddress now automatically detect when a branch needs to be switched to MakeClass(also known asDecomposedObj[ect]` mode).

• TChain now always checks the branch address; even in the case the address is set before any TTree is loaded. Specifically in addition to checking the address type in the case:

chain->LoadTree(0);
chain->SetBranchAdress(branch_name, &address);

now TChain will also check the addresses in the case:

chain->SetBranchAdress(branch_name, &address);
chain->LoadTree(0);

• TTree and TChain no longet override user provided sub-branch addresses. Prior to this release doing:

// Not setting the top level branch address.
chain->SetBranchAdress(sub_branch_name, &address);
chain->GetEntry(0);

Resulted in the address set to be forgotten. Note that a work-around was:

// Not setting the top level branch address.
chain->GetEntry(0);
chain->SetBranchAdress(sub_branch_name, &address);

But also the address needed to (in most cases) also be set again after each new tree was loaded.

Note that, the following:

chain->SetBranchAdress(sub_branch_name, &address);
chain->SetBranchAdress(top_level_branch_name, &other_address);
chain->GetEntry(0);

will result (as one would expect) with the first SetBranchAddress being ignored/over-ridden.

RDataFrame

• For some TTrees, RDataFrame’s GetColumnNames method returns multiple valid spellings for a given column. For example, leaf "l" under branch "b" might now be mentioned as "l" as well as "b.l", while only one of the two spellings might have been recognized before.

Bugs and Issues fixed in this release

• [ROOT-9240] - Compiled program with libNew.so crash
• [ROOT-10702] - TTree Wrong data could be silently written if data-member of object has same name as another branch
• [ROOT-10796] - Bug in MakeProxy std::map<int,std::vector<double,*>>
• [ROOT-10800] - TClass::GetListOfAllPublicMethods() lists deleted copy constructor of std::unique_ptr
• [ROOT-10833] - PyROOT FutureWarning in ROOT.py
• [ROOT-10837] - hadd crashes when slow merging file with multiple array with same index
• [ROOT-10839] - Missing lock guard in THashTable
• [ROOT-10873] - thisroot.sh sets the wrong PYTHONPATH on LCG views
• [ROOT-10882] - Drawing crashes when histogram title contain special characters
• [ROOT-10927] - Dramatic increase of memory usage while reading trees containing histograms

HEAD of the v6-20-00-patches branch

These changes will be part of a future 6.20/10.