src/gromacs/utility/init.cpp

   1 /*
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   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
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  35 /*! \internal \file
  36  * \brief
  37  * Implements functions from init.h.
  38  *
  39  * \author Teemu Murtola <teemu.murtola@gmail.com>
  40  * \ingroup module_utility
  41  */
  42 #include "gmxpre.h"
  43
  44 #include "init.h"
  45
  46 #include "config.h"
  47
  48 #include "gromacs/utility/basedefinitions.h"
  49 #include "gromacs/utility/fatalerror.h"
  50 #include "gromacs/utility/gmxassert.h"
  51 #if GMX_LIB_MPI
  52 #include "gromacs/utility/gmxmpi.h"
  53 #endif
  54
  55 namespace gmx
  56 {
  57
  58 namespace
  59 {
  60 #if GMX_LIB_MPI
  61 //! Maintains global counter of attempts to initialize MPI
  62 int g_initializationCounter = 0;
  63 #endif
  64 }
  65
  66 void init(int *argc, char ***argv) // NOLINT(readability-non-const-parameter)
  67 {
  68 #if GMX_LIB_MPI
  69     int isInitialized = 0, isFinalized = 0;
  70     MPI_Finalized(&isFinalized);
  71     GMX_RELEASE_ASSERT(!isFinalized, "Invalid attempt to initialize MPI after finalization");
  72     MPI_Initialized(&isInitialized);
  73     if (isInitialized)
  74     {
  75         if (0 == g_initializationCounter)
  76         {
  77             // Some other code has already initialized MPI, so bump the counter so that
  78             // we know not to finalize MPI ourselves later.
  79             g_initializationCounter++;
  80         }
  81     }
  82     else
  83     {
  84 #ifdef GMX_FAHCORE
  85         fah_MPI_Init(argc, argv);
  86 #else
  87 #    if GMX_OPENMP
  88         /* Formally we need to use MPI_Init_thread and ask for MPI_THREAD_FUNNELED
  89          * level of thread support when using OpenMP. However, in practice we
  90          * have never seen any problems with just using MPI_Init(), and some MPI
  91          * versions that only return MPI_THREAD_SINGLE as their support level
  92          * still return an OK initialization code when we request MPI_THREAD_FUNNELED.
  93          *
  94          * To avoid requiring users to recompile and install new libraries for something
  95          * that probably isn't a problem, we don't make a fuss about it (no warning)
  96          * if MPI_Init_thread() returns ok. If it does not return OK we
  97          * call a second init call without thread support, but since the library
  98          * apparently tried to prevent this we do issue a warning in this case.
  99          *
 100          * support, and if that doesn't work we simply use the simple MPI_Init().
 101          * Note that MPICH does not allow us to call MPI_Query_thread() before
 102          * we have initialized the library, and calling MPI_Init twice could
 103          * be a bit fragile. However, some implementations also advice against
 104          * doing anything else after calling MPI_Finalize, so at the end of the
 105          * day we'll have to cross our fingers...
 106          */
 107         int provided, rc;
 108         rc = MPI_Init_thread(argc, argv, MPI_THREAD_FUNNELED, &provided);
 109         if (rc != 0 && provided < MPI_THREAD_FUNNELED)
 110         {
 111             gmx_warning("GROMACS was compiled with OpenMP support, but there is no thread support in the MPI library. Keep your fingers crossed.");
 112             MPI_Init(argc, argv);
 113         }
 114 #    else
 115         MPI_Init(argc, argv);
 116 #    endif
 117 #endif
 118     }
 119     // Bump the counter to record this initialization event
 120     g_initializationCounter++;
 121
 122 #else
 123     GMX_UNUSED_VALUE(argc);
 124     GMX_UNUSED_VALUE(argv);
 125 #endif
 126 }
 127
 128 void finalize()
 129 {
 130 #if GMX_LIB_MPI
 131     GMX_RELEASE_ASSERT(0 < g_initializationCounter, "Excess attempt to finalize MPI");
 132     // Bump the counter to record this finalization event
 133     g_initializationCounter--;
 134
 135     if (0 == g_initializationCounter)
 136     {
 137         /* We sync the processes here to try to avoid problems
 138          * with buggy MPI implementations that could cause
 139          * unfinished processes to terminate.
 140          */
 141         MPI_Barrier(MPI_COMM_WORLD);
 142
 143         /* Apparently certain mpich implementations cause problems
 144          * with MPI_Finalize. In that case comment out MPI_Finalize.
 145          */
 146         MPI_Finalize();
 147     }
 148 #endif
 149 }
 150
 151 } // namespace gmx