Changelog Arcane v2.X.X

This page contains the new features of each version of Arcane v2.X.X.

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Arcane Version 2.22.0 (03 March 2021)

New Features/Improvements:

• Support for protections/recoveries for AMR meshes
• Internal modifications for accelerator support, notably support for graphics cards (GPGPU).
• Removal of entity classes and families for Arcane::DualNode and Arcane::Link. These classes can be replaced by using Arcane::DoF.
• Partial support for mesh files in 'msh' format version 4.1.

Changes:

• [IMPORTANT] This version uses the new connectivity structures by default. This should normally not impact existing codes provided they do not use the internal Arcane classes that manage entities (such as Arcane::ItemInternal).
• Execution statistics on time spent in different entry points and modules displayed at the end of the calculation now contain the cumulative total over all executions (in case of using protection/recovery) and not just the statistics for the current execution.
• Simplification of the various mechanisms for initializing and executing code using Arcane (see arcanedoc_execution_launcher)

Fixes:

• Fixes a potential parallel issue during the creation of the directory for protections. It was possible for some processes to attempt to access this directory before its creation.
• Fixes the usage of the arcane_convert_mesh script used for mesh conversion.
• Re-enables the generation of documentation for services and modules provided by Arcane

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Arcane Version 2.20.0 (07 January 2021)

New Features/Improvements:

• Addition of a new interface 'Arcane::IAsyncParticleExchanger' allowing asynchronous particle exchange. A new service AsyncParticleExchanger implements this interface.
• Adds the possibility to delete additional memory possibly used by a variable via the method Arcane::IVariable::shrinkMemory()
• Start of support for 2D Cartesian mesh refinement. It is now possible to call Arcane::ICartesianMesh::refinePatch2D() to refine a part of the mesh
• Support for Arccore::MessagePassing::MessageId in serialization messages (Arccore::MessagePassing::ISerializeMessage)
• Support for Papi version 6.0.0 and recent PETSc versions for aleph

Changes:

• Unification of documentation between the CEA part and the common part
• Support for parallel unit tests (see arcanedoc_debug_perf_unit_tests_parallel)
• Modifications to the classes Arcane::IData, Arcane::ISerializedData to use Arccore::Ref for managing references
• Start of redesign of variable creation and memory management to eventually allow developers to add their own variables.

Fixes:

• Fixes crash when using PTScotch during partitioning in case of single-node redistribution.
• Correctly names the 'ArcaneConfigVersion.cmake' file to be able to use a version number for Arcane in the CMake command find_package().

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Arcane Version 2.19.0 (30 June 2020)

Note

Following changes in serialization, it is generally not possible to resume a calculation started with an earlier version using this version of Arcane.

Changes:

• To prepare for the modularization of Arcane, retrieving the subdomain (Arcane::ISubDomain) is deprecated via many classes (Arcane::IMesh, Arcane::IVariable, Arcane::ICaseOptions, ...). Codes that require an instance of Arcane::ISubDomain must now explicitly pass it to the methods or classes using it. Services and modules continue to have access to subdomains.
• Use of Arcane::MeshHandle instead of Arcane::IMesh. With the possibility of using services to create meshes, meshes are no longer created before services. The Arcane::MeshHandle class allows managing a reference to a mesh before it exists. This class must notably be used in the constructors of modules and services. The method Arcane::MeshHandle::mesh() allows retrieving the associated mesh if it has already been created.
• Use of the Arccore::Ref class to manage references to Arcane::IParallelMng. Consequently, the method Arcane::IParallelMng::createSubParallelMng() is declared deprecated and Arcane::IParallelMng::createSubParallelMngRef() must now be used.
• Modification of Arccore::Span2::operator[]() to return an Arccore::Span instead of Arccore::ArrayView. This allows consistency with other methods of Arccore::Span2.
• Modification of Arccore::ISerializer to support direct writing of arrays and check consistency between reading and writing a given value. This requires that the calls reserve()/put()/get() are consistent. For example, if the method Arccore::ISerializer::reserveArray() is used, Arccore::ISerializer::putArray() and Arccore::ISerializer::getArray() must subsequently be used. Following this modification, the methods Arccore::ISerializer::get() and Arccore::ISerializer::put() which took an Arccore::Span or Arccore::ArrayView as argument are deprecated.
• Use of a specific macro ARCANE_CHECK_MATH to test the validity of Arcane::math mathematical operations. Previously, this was done via the ARCANE_CHECK macro, but this could introduce side effects when comparing two calculations with and without this verification mode.

New Features/Improvements:

• Numerous improvements to message exchange:
  • Support for all Arcane::IParallelMng methods in hybrid and shared memory modes. In particular, some serialization methods were missing.
  • Support for user tags in point-to-point methods (send/receive)
  • Use of specific types to manage tags (Arccore::MessageTag) and ranks (Arccore::MessageRank). These types replace the 'Int32' type previously used.
  • Unification of point-to-point method management. The necessary parameters are managed by the Arccore::PointToPointMessageInfo class.
  • Support for MPI methods using an MPI_Message (MPI_Mprobe, MPI_Improbe, MPI_Imrecv, MPI_Mrecv). These methods ensure that an MPI_Recv corresponds to the MPI_Probe used previously. These mechanisms are also accessible in hybrid mode.
• Support for mesh partitioning in shared memory and hybrid modes
• Adds to the Metis partitioner a mode allowing a single process to be used for partitioning. Previously, a minimum of two processes had to be used (due to a bug in ParMetis)
• Correction of the algorithm ensuring that there are no empty partitions after using ParMetis.
• Preparation of Arccore::ISerializer to eventually support other data types (for example, 'Float32' or 'Float16')
• Records a hash of the variable name during serializations. This ensures that the correct variable is being deserialized.
• Various improvements to the JSON reader/writer
• Generates information in the logs after a repartitioning about the subdomains connected to a subdomain.
• Support for compilation via the 'spack' tool.
• In the dataset, adds the possibility to put a block <comment> below the root. This is useful if a module is not active but you want to keep its options. You simply need to place this option block between the <comment>and </comment> tags.
• [.Net] Generates nuget packages for wrapping usage. It is therefore possible to directly reference these packages rather than going to look for the .dll files directly. The use of nuget packages also allows automatic dependency management.
• [.Net] Transition to .Net Core version 3.1.

The following points are under development but not finalized:

• Management of mesh creation as a service. Eventually, only this mode will be available. It will notably allow the creation of specific mesh structures (for example, Cartesian).
• Redesign of initialization to allow Arcane to be used without going through a loop in time

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Arcane Version 2.18.0 (09 December 2019)

This version includes the following developments:

• Improvement of the implementation of the Arcane::HPReal class, which fixes some edge cases and adds support for multiplication and division
• Creation of a universal Arccore::Ref class to manage the lifetime of objects such as services. This class automatically destroys an object when there are no more references to it. Dynamically allocated services now use this class. For example:

  using namespace Arcane;
  ISubDomain* sd = ...;
  ServiceBuilder<IDataReader> sb(sd);
  IDataReader* old_reader = sb.createInstance(...); // Deprecated
  Arccore::Ref<IDataReader> new_reader = sb.createReference(...); // New mechanism.

  Via this Arccore::Ref class, an object no longer needs to be explicitly destroyed. The method Arccore::makeRef() allows creating a reference from a pointer allocated by 'operator new'.
• Partial redesign of the dataset option reading mechanism. The ultimate goal is to be able to use something other than XML for data input. The modifications mainly concern the base classes managing options and should not affect user code.
• Detects dataset options under the root that are not read and returns an error. The environment variable ARCANE_ALLOW_UNKNOWN_ROOT_ELEMENT allows displaying a warning instead of an error if set.
• [.Net] Transition to .Net Core version 3.0.
• [.Net] C# support for classes managing materials and environment and scalar variables on constituents.
• [.Net] Support for launching C# user extensions via the dotnet tool instead of mono, which allows debugging C# code via, for example, Visual Studio Code.
• Transition to Lima version 6.38.0, which allows reading files in mli2 format. This format uses a recent version of HDF5 and optimizes, in particular, the size of mesh files when there is a large number of empty groups.

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Arcane Version 2.17.0 (09 October 2019)

This version includes the following developments:

• [.Net] Redesign of the .Net environment to allow compilation either with mono or with the Microsoft dotnet implementation.
• [.Net] Standardization of initialization with or without the use of the .Net runtime.
• Addition in the 'samples' directory of an 'EOS' example showing how to make C++ services or classes accessible in C#.
• Strict application of XML conversion rules for reading the active attribute in the <module> element indicating whether a module is active or not. Now, only the values true, false, 0 or 1 are allowed. Previously, any value other than false was considered true.
• Support in MPI profiling via the OTF2 library for cases with load balancing and back-propagation.
• Possibility to destroy additional meshes via the Arcane::IMeshMng class:

  Arcane::ISubDomain* sd = ...;
  Arcane::IMesh* mesh_to_destroy = ...;
  sd->meshMng()->destroyMesh(mesh_to_destroy);

  The pointer mesh_to_destroy must no longer be used after calling the destruction method.
• Support in Arcane::mesh::BasicParticleExchanger for particles that are not in meshes (those for which Arcane::Particle::cell() returns a null mesh)
• Adds options in the 'BasicParticleExchanger' service to allow choosing the maximum number of messages to perform before reductions
• Adds an environment variable ARCANE_VARIABLE_SHRINK_MEMORY for testing, which, if set to 1, resizes the memory allocated by variables as little as possible after changing the number of entities
• In Aleph, MPI communicators are destroyed in the destructor of AlephKernel. This had been disabled for reasons of compatibility with PETSc and old MPI versions.

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Arcane Version 2.16.0 (18 July 2019)

This version includes the following developments:

• Addition of internal profiling for entry points and MPI calls. The trace format depends on the value of the environment variable that activates this feature: ARCANE_MESSAGE_PASSING_PROFILING=OTF2 or JSON (see environment variable documentation and performance analysis).
• Redesign of the C# wrapper. The wrapper is now composed of several modules (Arcane.Core, Arcane.Hdf5, and Arcane.Services) and the wrapped methods now use C# coding rules: they start with a capital letter.
• Addition of an Arcane::MeshHandle class to manage meshes before their effective creation. Eventually, this will allow meshes to be deleted and created via services.

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Arcane Version 2.15.0 (13 June 2019)

This version includes the following developments:

• Support for MPI messages larger than 2GB. This only concerns MPI_Send/MPI_Recv type messages and only if passing through Arcane::ISerializer.
• Completes the implementation of Arcane::IParallelMng in shared memory mode. All methods except Arcane::IParallelMng::createSubParallelMng() are implemented. The classes managing this parallelism mode are renamed and start with SharedMemory instead of Thread.
• Renaming of classes managing message exchange in MPI+Shared Memory mode. These classes have a name starting with Hybrid instead of MpiThread.
• Support for .NetCore in addition to mono for managing AXL files. Projects managing AXL files can therefore use either .NetFramework 4.5 (with mono) or .NetCoreApp 2.2 (with .NetCore). It is now essential to have the msbuild tool to compile with mono. By default, the .NetCore implementation is used.
• The Arccore::String class now considers arguments of type const char* to be encoded in UTF-8 and no longer in ISO-8859-1.
• The Arccore::String class now internally manages character strings larger than 2GB. Consequently, the method Arccore::String::len() is deprecated and must be replaced by the method Arccore::String::length() which returns an Int64.
• It is now possible to construct instances of Arccore::String from the C++17 std::string_view class. Consequently, the methods of Arccore::String that took a const char* and a length as arguments are deprecated and replaced by methods taking std::string_view as arguments.
• A reproducible mode for ParMetis has been developed that ensures the same partitioning between two executions by grouping the graph on a single processor. This mode should not be used when the number of cells is greater than a few tens of millions.

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Arcane Version 2.14.0 (04 March 2019)

This version includes the following developments:

• Integration of IFPEN developments concerning degree of freedom type entities ( Arcane::DoF class).
• Possibility to redirect listing outputs both to standard output (stdout) and to a file with the option of not having different verbosity levels. Following this change, if the environment variable ARCANE_PARALLEL_OUTPUT is set, subdomain 0 writes the listing to a file like the other subdomains (the files are named output...). To specify that you want to write a listing file, you must set the environment variable ARCANE_MASTER_HAS_OUTPUT_FILE or call the method Arcane::ITraceMngPolicy::setIsMasterHasOutputFile() before initialization (for example, by overriding Arcane::MainFactory).
• Transition to UTF-8 for all sources (Arcane, Arccore,...)
• Moving the 'arccore' sources to its own GIT repository and moving the sources of arcane/dof to arcane/mesh

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Arcane Version 2.13.0 (21 January 2019)

This version includes the following developments:

• [INCOMPATIBILITY] Modification of the begin() and end() methods for array and array view classes (Arccore::ArrayView, Arccore::ConstArrayView, Arccore::Span, Arccore::Array) to return an iterator instead of a pointer. If you want to retrieve a pointer, you must use the data() method instead.
• [INCOMPATIBILITY] Creation of Arccore::Array instances is forbidden. You must use either Arccore::UniqueArray or Arccore::SharedArray. The Arccore::Array class must be used by reference as an argument or return value.
• Partial transition of Arcane sources to UTF-8
• Transition to HDF5 version 1.10+ (instead of 1.8)
• Support for MED format meshes (format used by CEA/DEN, notably by the Salomé platform)
• Modification of the 'axldoc' generator to generate Doxygen files in Markdown format with the '.md' extension instead of .dox files

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Arcane Version 2.12.0 (11 December 2018)

This version includes the following developments:

• Improvement of variable visualization with the latest versions of totalview and addition of visualization for scalar variables
• Creation of an Arccore::Span2 class to manage views on 2D arrays with 64-bit sizes.
• Internal redesign of protections/recoveries to allow changing the number of subdomains in recovery.

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Arcane Version 2.11.0 (18 October 2018)

This version includes the following developments:

• Support for arrays (Arccore::Array) and character strings (Arccore::String) exceeding 2GB. Internally, the number of elements is now stored in 64 bits instead of 32 bits.
• Addition of the 'LargeArrayView' and 'ConstLargeArrayView' classes which are identical to 'ArrayView' and 'ConstArrayView' but use a 64-bit size.

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Arcane Version 2.10.1 (04 October 2018)

This version includes the following developments:

• Possibility to specify multiple interfaces for services via the ARCANE_REGISTER_SERVICE() macro. Previously, this was only possible via 'axl' files.
• Singleton services implementing multiple interfaces are created only once, and the interfaces therefore refer to the same instance. Previously, there were as many instances as there were interfaces.
• It is possible to specify in the 'axl' file that a service is a singleton (see arcanedoc_core_types_service_desc).
• Possibility to specify default values by category via a new defaultvalue element in 'axl' files. The category used during execution can be set for each code via the method Arcane::ICaseDocument::setDefaultCategory(). The page arcanedoc_core_types_axl_caseoptions_struct indicates how to add these default values.
• Possibility to load singleton services in the dataset like modules via a new services element in the <arcane>element (see arcanedoc_core_types_casefile_arcaneelement).

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Arcane Version 2.10.0 (September 2018)

This version includes the following developments:

• Creation of a new component 'Arccore' grouping the common Arcane part with Alien. This component contains part of 'arcane_utils' and 'arcane_mpi'. Consequently, base classes such as Arccore::String, Arccore::ArrayView, Arccore::Array are now in the 'Arccore' namespace instead of 'Arcane'. Via the C++ 'using' mechanism, these classes are also available in the Arcane namespace, so there should be no incompatibility with existing source code. The only condition is not to explicitly declare Arcane types but to use the header file 'arcane/utils/UtilsTypes.h'.
• Use of the 'libxml2' library to manage XML instead of the 'XercesC' library. This modification was made for two features not available in 'XercesC': XInclude support with XmlSchema and UTF-8 encoding of character strings.
• Construction of 'Arccore::Array' is deprecated. You must explicitly use either 'Arccore::UniqueArray' or 'Arccore::SharedArray'.
• Separation of the implementation of Arccore::UniqueArray from that of Arccore::SharedArray to avoid retaining information that is only useful for one or the other of these classes.
• Possibility to specify a number of threads between 1 and the maximum number of threads allocated during an Arcane::Parallel::ForEach loop. This is done via the Arcane::ParallelLoopOptions class.
• The 'arcane.pc' file generated for pkg-config is deprecated and no longer contains all the libraries used by Arcane. To have an equivalent feature, you must use 'cmake' with the '–find-package' option.
• Redesign of iterator management on array classes (Arccore::Array, Arccore::ArrayView, Arccore::ConstArrayView). The current iterators that returned a pointer are declared deprecated and replaced by an object of type Arccore::ArrayIterator. Returning a pointer could pose a problem in case of inheritance. For example:

  class A { ... };
  class B : public A { ... };
   
  Arcane::Array<B*> array_of_b;
  for( A* a : array_of_b){
    // Plantage si sizeof(A)!=sizeof(B)
  }

  The new iterator is shared among the three array classes and is of type std::random_iterator. Depending on the use case, the current code may be changed as follows:
  • Using begin() to retrieve a pointer to the start of the array: use data() instead:

    Arcane::ArrayView<Int32> a;
    Int32* v = a.begin(); // Obsolète
    Int32* v = a.data();  // OK.

  • Using begin()/end() in STL algorithms. In this case, you must replace these methods with std::begin() and std::end():

    Arcane::ArrayView<Int32> a;
    std::sort(a.begin(),a.end()); // Obsolète
    std::sort(std::begin(a),std::end(a)); // OK

  • Using in the case of a C++11 for-range loop. In this case, you must use the array's range method. For example:

    Arcane::ArrayView<Int32> a;
    for( Int32 x : a) {} // Obsolète
    for( Int32 x : a.range()) {} // OK

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Arcane Version 2.9.1 (June 2018)

This version includes the following developments:

• Possibility to change the default values of the dataset options. For more information, refer to section arcanedoc_core_types_axl_caseoptions_default_values.
• Adds the valueIfPresentOrArgument() method for simple, enumerated, or extended options. This allows replacing the following code:

  Real x = 3.2;
  if (options()->myOption.isPresent())
    x = options()->myOptions();

  with the following code:

  Real x = options()->myOption.valueIfPresentOrArgument(3.2);

• 64-bit support for the non-blocking particle exchanger (service * *NonBlockingParticleExchanger** implementing Arcane::IParticleExchanger). This allows exceeding 2^31 particles during an exchange.
• Adds the Arcane::ITimeLoopMng::stopReason() method, allowing knowledge of the reason for the code's termination. In particular, it is now possible to know if the last iteration is being executed when a maximum number of iterations is specified.
• In the dataset, in the list of modules to activate, it is now possible to specify the name (translated or name) of the Module's XML element instead of the module name. For example, for the Arcane protection/recovery module, whose name is 'ArcaneCheckpoint', we currently have:

  <cas codename="ArcaneTest" xml:lang="fr" codeversion="1.0">
    <arcane>
      <modules>
        <module name="ArcaneCheckpoint" actif="true"/>
      </modules>
    </arcane>
    ...
    <arcane-protections-reprises>
      <periode>3</periode>
    </arcane-protections-reprises>
  </cas>

  and now it is possible to replace it with:

  <cas codename="ArcaneTest" xml:lang="fr" codeversion="1.0">
    <arcane>
      <modules>
        <module name="arcane-protections-reprises" actif="true"/>
      </modules>
    </arcane>
    ...
    <arcane-protections-reprises>
      <periode>3</periode>
    </arcane-protections-reprises>
  </cas>

---

Arcane Version 2.8.0 (January 31, 2018)

This version includes the following developments:

• Addition for unit tests of two macros ASSERT_NEARLY_ZERO and ASSERT_NEARLY_ZERO_EPSILON, which allow comparing a value to zero.
• Compile-time determination of the types 'Arcane::Int16', 'Arcane::Int32', and 'Arcane::Int64'. Because of this, the file 'ArcaneGlobal.h' no longer includes the file 'limits.h'.

• By default, the length units specified in Lima format files (.unf, .mli, ...) are now always taken into account. Previously, it was necessary to set the value 1 to the 'use-unit' attribute (in English) or 'utilise-unite' (in French) in the <mesh> (in English) or <maillage> (in French) element. To recover the previous behavior, you must set the value '0' to this attribute. For example in French:

  <maillage utilise-unite="0">
  ...
  </maillage>

  or in English:

  <mesh use-unit="0">
  ...
  </mesh>

---

Arcane Version 2.7.0 (October 20, 2017)

This version includes the following developments regarding materials and environment:

• possibility to iterate only over pure or impure cells of a material or an environment.
• new mechanisms for looping over materials and environments
• start of vectorization support for materials and environment. For now, this support only concerns scalar variables and only on environment.

For more information on these concepts, refer to page arcanedoc_materials_loop.

---

Arcane Version 2.6.1 (September 18, 2017)

This version includes the following visible developments:

• In the dataset options, it no longer tolerates invalid characters at the end of the option string. For example, the string '12a3' was considered valid for an integer type option and its value was '12'. Now an error is returned in this case.

This version includes internal developments aimed at eventually removing the old connectivity access mechanisms.

---

Arcane Version 2.6.0 (August 22, 2017)

This version activates the new connectivity access mechanism. The old mechanism remains accessible. Since the two mechanisms use different memory management, connectivities are allocated using both the new and the old mechanism, resulting in an increase of about 1KB of memory per cell. For more information, refer to page arcanedoc_entities_connectivity_internal.

---

Arcane Version 2.5.2 (July 25, 2017)

This version contains the following developments:

• addition of an event management mechanism (see file "arcane/utils/Event.h" and the EventObservable class for a usage example)
• addition of events during variable addition/removal (Arcane::IVariableMng::onVariableAdded() and Arcane::IVariableMng::onVariableRemoved()) and during synchronizations (Arcane::IVariableSynchronizer::onSynchronized()).
• possibility to specify a static partitioner for loops using multi-threading. This allows for deterministic (i.e., repeatable) behavior between multiple executions provided the same number of threads is used.

  #include <arcane/Concurrency.h>
  using namespace Arcane;
  ParallelLoopOptions opt;
  opt.setPartitioner(ParallelLoopOptions::Partitioner::Static);
  TaskFactory::setDefaultParallelLoopOptions(opt);

• addition of a named barrier mechanism to ensure that all processes reach the same barrier:

  #include <arcane/Parallel.h>
  using namespace Arcane;
  IParallelMng* pm = ...;
  MessagePassing::namedBarrier(pm,"MyBarrier");

• possibility to mix declarations of material and environment variables (for scalar variables only). In this case, all variables are allocated on materials and environment. By default, this is not active because it consumes memory unnecessarily.

  using namespace Arcane::Materials;
  IMeshMaterialMng* mm = ...;
  mm->setAllocateScalarEnvironmentVariableAsMaterial(true);
  MaterialVariableCellReal mat_var(MaterialVariableBuildInfo(mm,"Var1"));
  EnvironmentVariableCellReal env_var(MaterialVariableBuildInfo(mm,"Var1"));
  // 'mat_var' and 'env var' are the same variables.

---

Arcane Version 2.5.1 (May 04, 2017)

This version contains only internal developments and does not add features directly accessible to users.

---

Arcane Version 2.5.0 (March 15, 2017)

This version integrates developments to decouple connectivity management from entity management. For memory saving reasons, the current mechanism allows all connectivities to be available for each entity type. Potentially, this means, for example, that a particle and a cell can have the same connectivities. For more information on the new mechanisms, refer to the following page arcanedoc_entities_connectivity_internal. In this 2.5.0 version, the new connectivities are not active (which corresponds to the ' –with-legacy-connectivity' configuration mode described on the previous link page), so the behavior of codes using Arcane should not change.

Other new features are:

• addition of an Item::isShared() method to indicate if an entity is shared by multiple subdomains. For example:

Cell cell = ...;
if (cell.isShared())
  info() << "Cell is shared";

• synchronization of multiple variables in a single MPI message is now active by default. For example:

VariableCellReal temperature = ...;
VariableCellReal3 cell_center = ...;
VariableCollection vars;
vars.add(temperature);
vars.add(cell_center);
mesh()->cellFamily()->synchronize(vars);

Note that if the collection specified in the parameter contains partial variables, the synchronization is done as before, variable by variable.

---

Arcane Version 2.4.2 (January 13, 2017)

• Adds the possibility to configure traces during execution by specifying a character string in the trace configuration format (as in the documentation arcanedoc_execution_traces). For example:

  using namespace Arcane;
  String x = "<?xml version=\"1.0\"?>\n"
   "<arcane-config>\n"
   "<traces>\n"
   "<trace-class name='MyTest2' info='true' debug='med' print-elapsed-time='true' print-class-name='false'/>\n"
   "</traces>\n"
   "</arcane-config>\n";
  ISubDomain* sd = ...;
  ITraceMng* tm = sd->traceMng();
  sd->application()->getTraceMngPolicy()->setClassConfigFromXmlBuffer(tm,x.utf8());

• Adds the possibility to display or not display the message class name in the traces for each trace message, as well as the elapsed time. For example:

  using namespace Arcane;
  ITraceMng* tm = ...;
  TraceClassConfig tcc = tm->classConfig("MyTest");
  tcc.setFlags(Trace::PF_ElapsedTime|Trace::PF_NoClassName);
  tm->setClassConfig("MyTest",tcc);

• Adds an Arcane::IMeshUtilities::mergeNodes() method allowing the merging of nodes two by two.
• The internal entity compaction mechanism has been rewritten to be more easily configurable by entity family and more easily extensible if a new entity family type is added.

---

Arcane Version 2.4.1 (December 01, 2016)

• Support for the Arcane::MeshMaterialVariableRef::synchronize() method for variables only on environment.
• Adds a method on material variables to fill partial values with the value of the parent component cell. This allows filling material values with environment values or environment values with global values. The method is called Arcane::Materials::MeshMaterialVariableRef::fillPartialValuesWithSuperValues().
• Adds constant STL iterators for the Arcane::ItemVectorView class. This allows using STL algorithms with this class. For example:

  using namespace Arcane;
  ItemVector v1;
  ItemGroup group1;
  ItemVectorView group_view = group1.view();
  for( Item item : v1.view() ){
    // Regarde si 'item' est dans le groupe 'group1'.
    auto iter = std::find(group_view.begin(),group_view().end,item);
    if (iter!=group_view.end()){
      // Trouvé.
    }
  }
  for( Item item : group1.view() ){
    info() << "Item=" << ItemPrinter(item);
  }

• Adds the possibility to specify its own connectivity calculation function for Arcane::ItemPairGroup. The ItemPairGroup class documentation contains an example of such a calculation.
• Adds several options in the partitioning services:
  • for Parmetis, the possibility to write the graph to a file and specify the tolerance,
  • for PTScotch, the possibility to write the graph to a file and check the graph consistency.

---

Arcane Version 2.4.0 (November 2016)

• Support for variables only on environment. These variables are used like material variables but only have values on environment and global cells. Therefore, they should not be indexed with material cells (MatCell) under penalty of causing an illegal memory access. The declaration of these variables is done as follows:

  using namespace Arcane;
  EnvironmentVariableCellReal pressure(VariableBuildInfo(mesh,"Pressure"));
  IMeshEnvironment* env = ...;
  ENUMERATE_ENVCELL(ienvcell,env){
    pressure[ienvcell] = 2.0;
  }

• Support for repartitioning and load balancing while preserving material information. Partial values of material and environment cells are also preserved.
• Internal redesign of entity exchange management during repartitioning. The goal is to be able to more easily add new entity families or change the processing of one of them. This modification has no impact on existing code.

---

Arcane Version 2.3.9 (September 2016)

• Improvement of vectorization {#arcanedoc_news_changelog_version239_simd}
• Possibility to choose a specific allocator (implementing the IMemoryAllocator interface) for the Array and UniqueArray classes. An implementation managing alignment (Arcane::AlignedMemoryAllocator) is available and guarantees that the address of the allocated memory is a multiple of a certain value. For now, the only valid value for alignment is 64, and you must use the Arcane::AlignedMemoryAllocator::Simd() allocator to retrieve this allocator with this alignment. In addition to aligning the memory, this allocator guarantees that the size of the allocated memory is a multiple of the alignment. For example, the following code guarantees alignment:

  using namespace Arcane;
  UniqueArray<Real> x(AlignedMemoryAllocator::Simd());
  x.resize(25);
  // &x[0] is a multiple of 64.
  // A real taking 8 bytes, the capacity of x is a
  // multiple of (64 / 8), so x.capacity()>=32 (since 32 is the
  // first multiple of 8 greater than 25).

  The 64-byte alignment allows using all vectorization mechanisms available in Arcane to date, namely SSE, AVX, and AVX512.
• 1D and 2D array variables, as well as scalar and array variables on mesh entities, are now always allocated with the Arcane::AlignedMemoryAllocator::Simd() allocator.
• Entity indices of an ItemGroup are now always allocated with the Arcane::AlignedMemoryAllocator::Simd() allocator. Note that this is not the case for Arcane::ItemVector.
• The various macros used to manage enumeration with vectorization (ENUMERATE_SIMD_CELL, ENUMERATE_SIMD_NODE, ...) now require aligned arrays. If this is not the case, it causes an exception during execution.

  using namespace Arcane;
  CellGroup cells = ...;
  CellVector vec_cells = ...;
  ENUMERATE_SIMD_CELL(ivcell,cells){ // OK because a CellGroup is always aligned
  }
  ENUMERATE_SIMD_CELL(ivcell,vec_cells){ // ERROR because a CellVector is not always aligned
  }

• Using the Parallel::Foreach() methods on entity groups guarantees that iterations will be performed on multiples of 8 values. It is thus valid to write the following code:

  using namespace Arcane;
  CellGroup cells = ...;
  Parallel::Foreach(cells,[this](CellVectorView cvv){
    ENUMERATE_SIMD_CELL(ivcell,cvv){
      SimdCell cell = *ivcell;
      ...
    }
  }

• Adds support for AVX512 type vectorization and removes vectorization specific to Intel Knight Corner (KNC) processors. AVX512 is supported starting from Xeon Skylake and on XeonPhi processors starting from Intel Knight Landing (KNL).
• Allows multiple types of vectorization at once via Arcane's vectorization classes. For example, on Haswell machines that support AVX and SSE, the SSESimdReal and AVXSimdReal classes are always available. In previous versions of Arcane, only the most performant vectorization type was available (AVX512 > AVX > SSE).

Various improvements {#arcanedoc_news_changelog_version239_misc}

• Support for the C++11 std::move() semantics for the UniqueArray class. This allows, among other things, returning UniqueArrays without performing memory copying, and implementing std::swap() in an optimized manner.
• Adds optimized versions to exchange the values of two mesh variables (scalar or array) via a swapValues() method. This method allows exchanging only the pointers containing the memory areas of the two variables without copying. For example

  using namespace Arcane;
  VariableCellReal temperature = ...;
  VariableCellReal old_temperature = ...;
    VariableCellArrayReal energy = ...; // 1D variable on meshes
  VariableCellArrayReal old_energy = ...;
  old_temperature.swapValues(temperature);
  old_energy.swapValues(energy);

• Upgrade to version 1.11.4 of hwloc.
• [C#] In Arcane.Curves, support for curves with multiple values per iteration (2D curves).
• Uses real time (elapsed) instead of CPU time for end-of-calculation statistics. Real time is more accurate than CPU time and is independent of the number of threads used. It is possible to revert to using CPU time by setting the ARCANE_USE_VIRTUAL_TIMER environment variable.