Create Connectivity.java and be able to compile/run java files

Signed-off-by: vdhyasani17 <[email protected]>

Implement the code for Connectivity.java

Add comments to explain the functionality

Signed-off-by: vdhyasani17 <[email protected]>

Make communication non-blocking by using iSend and iRecv

Fix comment semantics and structure

Add -v verbose check

Signed-off-by: vdhyasani17 <[email protected]>

Author: Luke Robison

examples/Connectivity.java

@@ -0,0 +1,86 @@
+/*
+ * Test the connectivity between all processes
+ */
+
+import mpi.*;
+import java.nio.IntBuffer;
+
+class Connectivity {
+    public static void main(String args[]) throws MPIException {
+        MPI.Init(args);
+
+        /*
+         * MPI.COMM_WORLD is the communicator provided when MPI is
+         * initialized. It contains all the processes that are created
+         * upon program execution.
+         */
+        int myRank = MPI.COMM_WORLD.getRank();
+        int numProcesses = MPI.COMM_WORLD.getSize();
+        Status status;
+        boolean verbose = false;
+        int peerProcess;
+        String processorName = MPI.getProcessorName();
+
+        for (String arg : args) {
+            if (arg.equals("-v") || arg.equals("--verbose")) {
+                verbose = true;
+                break;
+            }
+        }
+
+        for (int i = 0; i < numProcesses; i++) {
+            /* Find current process */
+            if (myRank == i) {
+                /* send to and receive from all higher ranked processes */
+                for (int j = i + 1; j < numProcesses; j++) {
+                    if (verbose)
+                        System.out.printf("Checking connection between rank %d on %s and rank %d\n", i, processorName,
+                                j);
+
+                    /*
+                     * rank is the Buffer passed into iSend to send to rank j.
+                     * rank is populated with myRank, which is the data to send off
+                     * peer is the Buffer received from rank j from iRecv
+                     */
+                    IntBuffer rank = MPI.newIntBuffer(1);
+                    IntBuffer peer = MPI.newIntBuffer(1);
+                    rank.put(0, myRank);
+
+                    /*
+                     * To avoid deadlocks, use non-blocking communication iSend and iRecv
+                     * This will allow the program to progress, in the event that
+                     * two ranks both send to each other at the same time and could
+                     * potentially cause deadlock. The ranks can send their requests
+                     * without halting the program and immediately
+                     */
+                    Request sendReq = MPI.COMM_WORLD.iSend(rank, 1, MPI.INT, j, myRank);
+                    Request recvReq = MPI.COMM_WORLD.iRecv(peer, 1, MPI.INT, j, j);
+                    sendReq.waitFor();
+                    recvReq.waitFor();
+                }
+            } else if (myRank > i) {
+                IntBuffer rank = MPI.newIntBuffer(1);
+                IntBuffer peer = MPI.newIntBuffer(1);
+                rank.put(0, myRank);
+
+                /* receive from and reply to rank i */
+                MPI.COMM_WORLD.iRecv(peer, 1, MPI.INT, i, i).waitFor();
+                MPI.COMM_WORLD.iSend(rank, 1, MPI.INT, i, myRank).waitFor();
+            }
+        }
+
+        /* Wait for all processes to reach barrier before proceeding */
+        MPI.COMM_WORLD.barrier();
+
+        /*
+         * Once all ranks have reached the barrier,
+         * have only one process print out the confirmation message.
+         * In this case, we are having the "master" process print the message.
+         */
+        if (myRank == 0) {
+            System.out.printf("Connectivity test on %d processes PASSED.\n", numProcesses);
+        }
+
+        MPI.Finalize();
+    }
+}

ompi/mca/coll/han/coll_han_alltoallv.c

@@ -804,6 +804,7 @@ int mca_coll_han_alltoallv_using_smsc(
     low_gather_out = malloc(sizeof(*low_gather_out) * low_size);
     struct peer_data *peers = malloc(sizeof(*peers) * low_size);
     opal_datatype_t *peer_send_types = malloc(sizeof(*peer_send_types) * low_size);
+    bool have_bufs_and_types = false;
 
     low_gather_in.serialization_buffer = serialization_buf;
     low_gather_in.sbuf = (void*)sbuf; // cast to discard the const
@@ -896,6 +897,7 @@ int mca_coll_han_alltoallv_using_smsc(
         peers[jrank].sendtype = &peer_send_types[jrank];
     }
 
+    have_bufs_and_types = true;
     send_from_addrs = malloc(sizeof(*send_from_addrs)*low_size);
     recv_to_addrs = malloc(sizeof(*recv_to_addrs)*low_size);
     send_counts = malloc(sizeof(*send_counts)*low_size);
@@ -964,14 +966,16 @@ int mca_coll_han_alltoallv_using_smsc(
         free(recv_types);
     }
 
-    for (int jlow=0; jlow<low_size; jlow++) {
-        if (jlow != low_rank) {
-            OBJ_DESTRUCT(&peer_send_types[jlow]);
-        }
+    if (have_bufs_and_types) {
+        for (int jlow=0; jlow<low_size; jlow++) {
+            if (jlow != low_rank) {
+                OBJ_DESTRUCT(&peer_send_types[jlow]);
+            }
 
-        for (int jbuf=0; jbuf<2; jbuf++) {
-            if (peers[jlow].map_ctx[jbuf]) {
-                mca_smsc->unmap_peer_region(peers[jlow].map_ctx[jbuf]);
+            for (int jbuf=0; jbuf<2; jbuf++) {
+                if (peers[jlow].map_ctx[jbuf]) {
+                    mca_smsc->unmap_peer_region(peers[jlow].map_ctx[jbuf]);
+                }
             }
         }
     }