Add a test for hanging in a loop over mpi_reduce

This commit was SVN r20798.

orte/test/mpi/Makefile

@@ -1,4 +1,4 @@
-PROGS = mpi_no_op mpi_barrier hello hello_nodename abort multi_abort simple_spawn concurrent_spawn spawn_multiple mpi_spin delayed_abort loop_spawn loop_child bad_exit pubsub hello_barrier segv accept connect hello_output hello_show_help crisscross read_write ziatest slave_spawn slave cell_spawn
+PROGS = mpi_no_op mpi_barrier hello hello_nodename abort multi_abort simple_spawn concurrent_spawn spawn_multiple mpi_spin delayed_abort loop_spawn loop_child bad_exit pubsub hello_barrier segv accept connect hello_output hello_show_help crisscross read_write ziatest slave_spawn slave cell_spawn reduce-hang
 
 all: $(PROGS)
 

orte/test/mpi/reduce-hang.c

@@ -0,0 +1,30 @@
+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+    long count = 0;
+    int i = 8, j;
+    int self;
+    int do_barrier = 0;
+    
+    if (getenv("DO_BARRIER")) {
+        do_barrier = 1;
+    }
+    
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &self);
+    while (1) {
+        MPI_Reduce(&i, &j, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
+        if (do_barrier) {
+            MPI_Barrier(MPI_COMM_WORLD);
+        }
+        if (0 == (++count % 10000)) {
+            fprintf(stderr, "%ld still going at %d\n", self, count);
+        }
+    }
+    MPI_Finalize();
+
+    return 0;
+}