Merge branch 'master' of https://github.com/csc-training/hpc-python

Author: jussienko

answers/ex29.py

@@ -1,5 +1,6 @@
 from mpi4py import MPI
 import numpy
+from sys import stdout
 
 comm = MPI.COMM_WORLD
 rank = comm.Get_rank()
@@ -31,6 +32,7 @@
                 (rank, len(data), tgt))
 
 # ... wait for every rank to finish ...
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print("")
@@ -53,6 +55,7 @@
                 (rank, len(data), tgt))
 
 # ... wait for every rank to finish ...
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print("")
@@ -78,6 +81,7 @@
             (rank, len(data), tgt))
 
 # ... wait for every rank to finish ...
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print("")

answers/ex31a.py

@@ -1,5 +1,6 @@
 from mpi4py import MPI
 import numpy
+from sys import stdout
 
 comm = MPI.COMM_WORLD
 rank = comm.Get_rank()
@@ -30,6 +31,7 @@
     print("  Rank %d: received an array filled with %ds." % (rank, buff[0]))
 
 # ... wait for every rank to finish ...
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print("")
@@ -51,6 +53,7 @@
     print("  Rank %d: received an array filled with %ds." % (rank, buff[0]))
 
 # ... wait for every rank to finish ...
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print("")

answers/ex32.py

@@ -1,5 +1,6 @@
 from mpi4py import MPI
 import numpy
+from sys import stdout
 
 comm = MPI.COMM_WORLD
 rank = comm.Get_rank()
@@ -26,13 +27,15 @@
 buff = numpy.full(8, -1, int)
 
 # ... wait for every rank to finish ...
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print('')
     print('-' * 32)
     print('')
     print('Data vectors:')
 print('  Task {0}: {1}'.format(rank, data))
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print('')
@@ -44,6 +47,7 @@
 
 # ... wait for every rank to finish ...
 buff[:] = -1
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print('')
@@ -58,6 +62,7 @@
 
 # ... wait for every rank to finish ...
 buff[:] = -1
+stdout.flush()
 comm.barrier()
 if rank == 0:
     print('')

demos/mpi-example.py

@@ -0,0 +1,24 @@
+from mpi4py import MPI
+import numpy
+
+comm = MPI.COMM_WORLD
+rank = comm.Get_rank()
+size = comm.Get_size()
+
+# Send and receive buffers
+n = 100000
+data = numpy.full(n, rank, int)
+buff = numpy.full(n, -1, int)
+
+# Destination and source for messages (using PROC_NULL for out-of-bounds)
+tgt = rank + 1
+src = rank - 1
+if tgt >= size:
+    tgt = MPI.PROC_NULL
+if src < 0:
+    src = MPI.PROC_NULL
+
+# Use a single MPI call to do communication
+comm.Sendrecv(data, dest=tgt, recvbuf=buff, source=src)
+print("  Rank %d: receive buffer is filled with %ds." % (rank, buff[0]))
+