src/gromacs/utility/init.cpp

   1 /*
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   7  * top-level source directory and at http://www.gromacs.org.
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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 } // namespace
  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 #    if GMX_OPENMP
  85         /* Formally we need to use MPI_Init_thread and ask for MPI_THREAD_FUNNELED
  86          * level of thread support when using OpenMP. However, in practice we
  87          * have never seen any problems with just using MPI_Init(), and some MPI
  88          * versions that only return MPI_THREAD_SINGLE as their support level
  89          * still return an OK initialization code when we request MPI_THREAD_FUNNELED.
  90          *
  91          * To avoid requiring users to recompile and install new libraries for something
  92          * that probably isn't a problem, we don't make a fuss about it (no warning)
  93          * if MPI_Init_thread() returns ok. If it does not return OK we
  94          * call a second init call without thread support, but since the library
  95          * apparently tried to prevent this we do issue a warning in this case.
  96          *
  97          * support, and if that doesn't work we simply use the simple MPI_Init().
  98          * Note that MPICH does not allow us to call MPI_Query_thread() before
  99          * we have initialized the library, and calling MPI_Init twice could
 100          * be a bit fragile. However, some implementations also advice against
 101          * doing anything else after calling MPI_Finalize, so at the end of the
 102          * day we'll have to cross our fingers...
 103          */
 104         int provided, rc;
 105         rc = MPI_Init_thread(argc, argv, MPI_THREAD_FUNNELED, &provided);
 106         if (rc != 0 && provided < MPI_THREAD_FUNNELED)
 107         {
 108             gmx_warning(
 109                     "GROMACS was compiled with OpenMP support, but there is no thread support in "
 110                     "the MPI library. Keep your fingers crossed.");
 111             MPI_Init(argc, argv);
 112         }
 113 #    else
 114         MPI_Init(argc, argv);
 115 #    endif
 116     }
 117     // Bump the counter to record this initialization event
 118     g_initializationCounter++;
 119
 120 #else
 121     GMX_UNUSED_VALUE(argc);
 122     GMX_UNUSED_VALUE(argv);
 123 #endif
 124 }
 125
 126 void finalize()
 127 {
 128 #if GMX_LIB_MPI
 129     GMX_RELEASE_ASSERT(0 < g_initializationCounter, "Excess attempt to finalize MPI");
 130     // Bump the counter to record this finalization event
 131     g_initializationCounter--;
 132
 133     if (0 == g_initializationCounter)
 134     {
 135         /* We sync the processes here to try to avoid problems
 136          * with buggy MPI implementations that could cause
 137          * unfinished processes to terminate.
 138          */
 139         MPI_Barrier(MPI_COMM_WORLD);
 140
 141         /* Apparently certain mpich implementations cause problems
 142          * with MPI_Finalize. In that case comment out MPI_Finalize.
 143          */
 144         MPI_Finalize();
 145     }
 146 #endif
 147 }
 148
 149 } // namespace gmx