src/gromacs/utility/init.cpp

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