auto detect if we are running on a shared filesystem and remove the cmdline option

(cherry picked from commit a9094a81)

docs/user-guide/command-line/command-line.tex

@@ -23,10 +23,6 @@ Override a parameter (or define a new one) specified in the XML file.
 \hangindent=1.5cm
 Override a solverinfo (or define a new one) specified in the XML file.
 
-\lstinline[style=BashInputStyle]{--shared-filesystem}\\
-\hangindent=1.5cm
-By default when running in parallel the complete mesh is loaded by all processes, although partitioning is done uniquely on the root process only and communicated to the other processes. Each process then writes out its own partition to the local working directory. This is the most robust approach in accounting for systems where the distributed nodes do not share a common filesystem. In the case that there is a common filesystem, this option forces only the root process to load the complete mesh, perform partitioning and write out the session files for all partitions. This avoids potential memory issues when multiple processes attempt to load the complete mesh on a single node.
-
 \lstinline[style=BashInputStyle]{--npx [int]}\\
 \hangindent=1.5cm
 When using a fully-Fourier expansion, specifies the number of processes to use in the x-coordinate direction.

library/LibUtilities/BasicUtils/SessionReader.cpp

@@ -194,6 +194,8 @@ namespace Nektar
             // Create communicator
             CreateComm(argc, argv);
 
+            TestSharedFilesystem();
+
             // If running in parallel change the default global sys solution
             // type.
             if (m_comm->GetSize() > 1)
@@ -237,6 +239,8 @@ namespace Nektar
                 }
             }
 
+            TestSharedFilesystem();
+
             // If running in parallel change the default global sys solution
             // type.
             if (m_comm->GetSize() > 1)
@@ -310,6 +314,43 @@ namespace Nektar
         }
 
 
+        void SessionReader::TestSharedFilesystem()
+        {
+            m_sharedFilesystem = false;
+
+            if (m_comm->GetSize() > 1)
+            {
+                if (m_comm->GetRank() == 0)
+                {
+                    std::ofstream testfile ("shared-fs-testfile");
+                    testfile << "" << std::endl;
+                    testfile.close();
+                }
+                m_comm->Block();
+
+                std::ifstream testfile("shared-fs-testfile");
+                int exists = (bool) testfile;
+                m_comm->AllReduce(exists, LibUtilities::ReduceSum);
+
+                m_sharedFilesystem = (exists == m_comm->GetSize());
+
+                if ((m_sharedFilesystem && m_comm->GetRank() == 0) || !m_sharedFilesystem)
+                {
+                    std::remove("shared-fs-testfile");
+                }
+            }
+            else
+            {
+                m_sharedFilesystem = false;
+            }
+
+            if (m_verbose && m_comm->GetRank() == 0 && m_sharedFilesystem)
+            {
+                cout << "shared filesystem detected" << endl;
+            }
+        }
+
+
         /**
          * @brief Parses the command-line arguments for known options and
          * filenames.
@@ -327,7 +368,6 @@ namespace Nektar
                                  "override a SOLVERINFO property")
                 ("parameter,P",  po::value<vector<std::string> >(),
                                  "override a parameter")
-                ("shared-filesystem,s", "Using shared filesystem.")
                 ("npx",          po::value<int>(),
                                  "number of procs in X-dir")
                 ("npy",          po::value<int>(),
@@ -619,6 +659,10 @@ namespace Nektar
             return m_comm;
         }
 
+        bool SessionReader::GetSharedFilesystem()
+        {
+            return m_sharedFilesystem;
+        }
 
         /**
          * This routine finalises any parallel communication.
@@ -1657,7 +1701,7 @@ namespace Nektar
             {
                 SessionReaderSharedPtr vSession     = GetSharedThisPtr();
                 int nParts = vCommMesh->GetSize();
-                if (DefinesCmdLineArgument("shared-filesystem"))
+                if (m_sharedFilesystem)
                 {
                     CommSharedPtr vComm = GetComm();
                     vector<unsigned int> keys, vals;

library/LibUtilities/BasicUtils/SessionReader.h

@@ -195,6 +195,8 @@ namespace Nektar
             LIB_UTILITIES_EXPORT const std::string  GetSessionNameRank() const;
             /// Returns the communication object.
             LIB_UTILITIES_EXPORT CommSharedPtr &GetComm();
+            /// Returns the communication object.
+            LIB_UTILITIES_EXPORT bool GetSharedFilesystem();
             /// Finalises the session.
             LIB_UTILITIES_EXPORT void Finalise();
 
@@ -457,6 +459,8 @@ namespace Nektar
             FilterMap                                 m_filters;
             /// Be verbose
             bool                                      m_verbose;
+            /// Running on a shared filesystem
+            bool                                      m_sharedFilesystem;
             /// Map of original composite ordering for parallel periodic bcs.
             CompositeOrdering                         m_compOrder;
             /// Map of original boundary region ordering for parallel periodic
@@ -481,6 +485,8 @@ namespace Nektar
             /// Returns a shared pointer to the current object.
             inline SessionReaderSharedPtr GetSharedThisPtr();
 
+            LIB_UTILITIES_EXPORT void TestSharedFilesystem();
+
             /// Parse the program arguments and fill #m_cmdLineOptions
             std::vector<std::string> ParseCommandLineArguments(
                 int argc, char *argv[]);

library/SolverUtils/EquationSystem.cpp

@@ -125,7 +125,7 @@ namespace Nektar
             m_fld = MemoryManager<LibUtilities::FieldIO>
                 ::AllocateSharedPtr(
                     m_session->GetComm(),
-                    m_session->DefinesCmdLineArgument("shared-filesystem"));
+                    m_session->GetSharedFilesystem());
 
             // Read the geometry and the expansion information
             m_graph = SpatialDomains::MeshGraph::Read(m_session);

utilities/FieldConvert/FieldConvert.cpp

@@ -85,7 +85,6 @@ int main(int argc, char* argv[])
                 "Print options for a module.")
         ("module,m", po::value<vector<string> >(),
                 "Specify modules which are to be used.")
-        ("shared-filesystem,s", "Using shared filesystem.")
         ("useSessionVariables",
                 "Use variables defined in session for output")
         ("verbose,v",

utilities/FieldConvert/InputModules/InputXml.cpp

@@ -234,11 +234,6 @@ void InputXml::Process(po::variables_map &vm)
         cmdArgs.push_back("--verbose");
     }
 
-    if(vm.count("shared-filesystem"))
-    {
-        cmdArgs.push_back("--shared-filesystem");
-    }
-
     if(vm.count("part-only"))
     {
         cmdArgs.push_back("--part-only");