A first cut at a possible solution for the missing requests

from the message queues (a debugging feature). With this approach
all blocking (single threaded) requests are allocated from the main
freelist, so they will be accounted for during the message queues
investigation).

ompi/mca/pml/ob1/pml_ob1.h

@@ -208,6 +208,14 @@ extern int mca_pml_ob1_start( size_t count,
 
 extern int mca_pml_ob1_ft_event( int state );
 
+/**
+ * We will use these requests to hold on a traditionally allocated
+ * requests in order to allow the parallel debugger full access to the
+ * message queues (instead of allocating the requests on the stack).
+ */
+extern struct mca_pml_ob1_recv_request_t *mca_pml_ob1_recvreq;
+extern struct mca_pml_ob1_send_request_t *mca_pml_ob1_sendreq;
+
 END_C_DECLS
 
 struct mca_pml_ob1_pckt_pending_t {

ompi/mca/pml/ob1/pml_ob1_component.c

@@ -304,6 +304,15 @@ int mca_pml_ob1_component_fini(void)
     OBJ_DESTRUCT(&mca_pml_ob1.lock);
     OBJ_DESTRUCT(&mca_pml_ob1.send_ranges);
 
+    if( NULL != mca_pml_ob1_recvreq ) {
+        OBJ_DESTRUCT(mca_pml_ob1_recvreq);
+        mca_pml_ob1_recvreq = NULL;
+    }
+    if( NULL != mca_pml_ob1_sendreq ) {
+        OBJ_DESTRUCT(mca_pml_ob1_sendreq);
+        mca_pml_ob1_sendreq = NULL;
+    }
+
     if( NULL != mca_pml_ob1.allocator ) {
         (void)mca_pml_ob1.allocator->alc_finalize(mca_pml_ob1.allocator);
         mca_pml_ob1.allocator = NULL;

ompi/mca/pml/ob1/pml_ob1_irecv.c

@@ -32,6 +32,8 @@
 #include <alloca.h>
 #endif  /* HAVE_ALLOCA_H */
 
+mca_pml_ob1_recv_request_t *mca_pml_ob1_recvreq = NULL;
+
 int mca_pml_ob1_irecv_init(void *addr,
                            size_t count,
                            ompi_datatype_t * datatype,
@@ -92,10 +94,15 @@ int mca_pml_ob1_recv(void *addr,
                      struct ompi_communicator_t *comm,
                      ompi_status_public_t * status)
 {
-    mca_pml_ob1_recv_request_t *recvreq =
-        alloca(mca_pml_base_recv_requests.fl_frag_size);
+    mca_pml_ob1_recv_request_t *recvreq = mca_pml_ob1_recvreq;
     int rc;
 
+    if( NULL == recvreq ) {
+        MCA_PML_OB1_RECV_REQUEST_ALLOC(recvreq);
+        if (NULL == recvreq)
+            return OMPI_ERR_TEMP_OUT_OF_RESOURCE;
+        mca_pml_ob1_recvreq = recvreq;
+    }
     OBJ_CONSTRUCT(recvreq, mca_pml_ob1_recv_request_t);
 
     MCA_PML_OB1_RECV_REQUEST_INIT(recvreq, addr, count, datatype,

ompi/mca/pml/ob1/pml_ob1_isend.c

@@ -32,6 +32,8 @@
 #include <alloca.h>
 #endif  /* HAVE_ALLOCA_H */
 
+mca_pml_ob1_send_request_t *mca_pml_ob1_sendreq = NULL;
+
 int mca_pml_ob1_isend_init(void *buf,
                            size_t count,
                            ompi_datatype_t * datatype,
@@ -181,8 +183,7 @@ int mca_pml_ob1_send(void *buf,
     ompi_proc_t *dst_proc = ompi_comm_peer_lookup (comm, dst);
     mca_bml_base_endpoint_t* endpoint = (mca_bml_base_endpoint_t*)
                                         dst_proc->proc_endpoints[OMPI_PROC_ENDPOINT_TAG_BML];
-    mca_pml_ob1_send_request_t *sendreq =
-        alloca(mca_pml_base_send_requests.fl_frag_size);
+    mca_pml_ob1_send_request_t *sendreq = mca_pml_ob1_sendreq;
     int16_t seqn;
     int rc;
 
@@ -206,6 +207,11 @@ int mca_pml_ob1_send(void *buf,
 
     seqn = (uint16_t) OPAL_THREAD_ADD32(&ob1_comm->procs[dst].send_sequence, 1);
 
+    /**
+     * The immediate send will not have a request, so they are
+     * intracable from the point of view of any debugger attached to
+     * the parallel application.
+     */
     if (MCA_PML_BASE_SEND_SYNCHRONOUS != sendmode) {
         rc = mca_pml_ob1_send_inline (buf, count, datatype, dst, tag, seqn, dst_proc,
                                       endpoint, comm);
@@ -214,6 +220,13 @@ int mca_pml_ob1_send(void *buf,
         }
     }
 
+    if( NULL == sendreq ) {
+        MCA_PML_OB1_SEND_REQUEST_ALLOC(comm, dst, sendreq);
+        if (NULL == sendreq)
+            return OMPI_ERR_TEMP_OUT_OF_RESOURCE;
+        mca_pml_ob1_sendreq = sendreq;
+    }
+
     OBJ_CONSTRUCT(sendreq, mca_pml_ob1_send_request_t);
     sendreq->req_send.req_base.req_proc = dst_proc;
     sendreq->rdma_frag = NULL;