SST,MPI,DP: soft handle peer error

source/adios2/toolkit/sst/dp/mpi_dp.c

@@ -589,7 +589,7 @@ static int MpiWaitForCompletion(CP_Services Svcs, void *Handle_v)
     }
     else
     {
-        Svcs->verbose(Handle->CPStream, DPTraceVerbose,
+        Svcs->verbose(Handle->CPStream, DPCriticalVerbose,
                       "Remote memory read to rank %d with condition %d has FAILED"
                       "because of "
                       "writer failure\n",
@@ -628,7 +628,7 @@ static void MpiReadRequestHandler(CManager cm, CMConnection conn, void *msg_v, v
     if (!RequestedData)
     {
         PERFSTUBS_TIMER_STOP_FUNC(timer);
-        Svcs->verbose(StreamWR->Stream.CP_Stream, DPPerStepVerbose,
+        Svcs->verbose(StreamWR->Stream.CP_Stream, DPCriticalVerbose,
                       "Failed to read TimeStep %ld, not found\n", ReadRequestMsg->TimeStep);
         return;
     }
@@ -833,11 +833,42 @@ static void MpiNotifyConnFailure(CP_Services Svcs, DP_RS_Stream Stream_v, int Fa
                   FailedPeerRank);
 }
 
+/** MpiDisconnectWriterPerReader.
+ *
+ * This is called whenever a reader disconnect from a writer. This function
+ * simply disconnect the mpi communicator, it does not frees any data
+ * structure. We must do it in this way since:
+ *
+ * - There is the possibility of the failed peer to re-enter in the network.
+ * - We must disconnect the MPI port for that particular mpi reader task since
+ *   otherwise it the reader task might hung in mpi_finalize, in the case the
+ *   the failure leads to a application graceful exit.
+ */
+static void MpiDisconnectWriterPerReader(CP_Services Svcs, DP_WSR_Stream WSR_Stream_v)
+{
+    MpiStreamWPR StreamWPR = (MpiStreamWPR)WSR_Stream_v;
+    MpiStreamWR StreamWR = StreamWPR->StreamWR;
+
+    const int CohortSize = StreamWPR->Link.CohortSize;
+
+    Svcs->verbose(StreamWR->Stream.CP_Stream, DPTraceVerbose,
+                  "MpiDisconnectWriterPerReader invoked [rank:%d;cohortSize:%d]\n", CohortSize,
+                  StreamWR->Stream.Rank);
+
+    for (int i = 0; i < CohortSize; i++)
+    {
+        if (StreamWPR->CohortMpiComms[i] != MPI_COMM_NULL)
+        {
+            MPI_Comm_disconnect(&StreamWPR->CohortMpiComms[i]);
+        }
+    }
+}
+
 /**
  * MpiDestroyWriterPerReader.
  *
- * This is called whenever a reader disconnect from a writer. This function
- * also removes the StreamWPR from its own StreamWR.
+ * This is called by the MpiDestroyWriter function. This function will free any resource
+ * allocated to the particulare WriterPerReader instance (StreamWPR).
  */
 static void MpiDestroyWriterPerReader(CP_Services Svcs, DP_WSR_Stream WSR_Stream_v)
 {
@@ -846,6 +877,10 @@ static void MpiDestroyWriterPerReader(CP_Services Svcs, DP_WSR_Stream WSR_Stream
 
     const int CohortSize = StreamWPR->Link.CohortSize;
 
+    Svcs->verbose(StreamWR->Stream.CP_Stream, DPTraceVerbose,
+                  "MpiDestroyWriterPerReader invoked [rank:%d;cohortSize:%d]", CohortSize,
+                  StreamWR->Stream.Rank);
+
     for (int i = 0; i < CohortSize; i++)
     {
         if (StreamWPR->CohortMpiComms[i] != MPI_COMM_NULL)
@@ -871,6 +906,9 @@ static void MpiDestroyWriter(CP_Services Svcs, DP_WS_Stream WS_Stream_v)
 {
     MpiStreamWR StreamWR = (MpiStreamWR)WS_Stream_v;
 
+    Svcs->verbose(StreamWR->Stream.CP_Stream, DPTraceVerbose,
+                  "MpiDestroyWriter invoked [rank:%d]\n", StreamWR->Stream.Rank);
+
     pthread_mutex_lock(&StreamWR->MutexReaders);
     while (!TAILQ_EMPTY(&StreamWR->Readers))
     {
@@ -900,6 +938,10 @@ static void MpiDestroyWriter(CP_Services Svcs, DP_WS_Stream WS_Stream_v)
 static void MpiDestroyReader(CP_Services Svcs, DP_RS_Stream RS_Stream_v)
 {
     MpiStreamRD StreamRS = (MpiStreamRD)RS_Stream_v;
+
+    Svcs->verbose(StreamRS->Stream.CP_Stream, DPTraceVerbose,
+                  "MpiDestroyReader invoked [rank:%d]\n", StreamRS->Stream.Rank);
+
     const int CohortSize = StreamRS->Link.CohortSize;
 
     for (int i = 0; i < CohortSize; i++)
@@ -930,7 +972,7 @@ extern CP_DP_Interface LoadMpiDP()
         .getPriority = MpiGetPriority,
         .destroyReader = MpiDestroyReader,
         .destroyWriter = MpiDestroyWriter,
-        .destroyWriterPerReader = MpiDestroyWriterPerReader,
+        .destroyWriterPerReader = MpiDisconnectWriterPerReader,
         .notifyConnFailure = MpiNotifyConnFailure,
     };