mpi-pthreads-pie-collective:
  needs support of PTHREAD_MUTEX_INITIALIZER:
  pthread_mutex_t mypi_mutex = PTHREAD_MUTEX_INITIALIZER;
  
mpi-pthreads-pthreads.c:
  needs support of MPI features:
  MPI_Init_thread, MPI_Abort, enumerators such as MPI_THREAD_MULTIPLE.

mpithreads_both.c:
  has a memory leak problem, needs to debug.