Fix

java/runtime/src/main/java/org/ray/runtime/raylet/RayletClientImpl.java

@@ -154,6 +154,7 @@ private static TaskSpec parseTaskSpecFromFlatbuffer(ByteBuffer bb) {
     UniqueId actorId = UniqueId.fromByteBuffer(info.actorIdAsByteBuffer());
     UniqueId actorHandleId = UniqueId.fromByteBuffer(info.actorHandleIdAsByteBuffer());
     int actorCounter = info.actorCounter();
+    int numReturns = info.numReturns();
 
     // Deserialize new actor handles
     UniqueId[] newActorHandles = IdUtil.getUniqueIdsFromByteBuffer(
@@ -177,8 +178,6 @@ private static TaskSpec parseTaskSpecFromFlatbuffer(ByteBuffer bb) {
         args[i] = FunctionArg.passByValue(data);
       }
     }
-    // Deserialize return ids
-    int numReturns = info.numReturns();
 
     // Deserialize required resources;
     Map<String, Double> resources = new HashMap<>();
@@ -211,6 +210,7 @@ private static ByteBuffer convertTaskSpecToFlatbuffer(TaskSpec task) {
     final int actorIdOffset = fbb.createString(task.actorId.toByteBuffer());
     final int actorHandleIdOffset = fbb.createString(task.actorHandleId.toByteBuffer());
     final int actorCounter = task.actorCounter;
+    final int numReturnsOffset = task.numReturns;
 
     // Serialize the new actor handles.
     int newActorHandlesOffset
@@ -234,9 +234,6 @@ private static ByteBuffer convertTaskSpecToFlatbuffer(TaskSpec task) {
     }
     int argsOffset = fbb.createVectorOfTables(argsOffsets);
 
-    // Serialize returns
-    int returnsOffset = fbb.createString(IdUtil.concatIds(task.returnIds));
-
     // Serialize required resources
     // The required_resources vector indicates the quantities of the different
     // resources required by this task. The index in this vector corresponds to
@@ -292,7 +289,7 @@ private static ByteBuffer convertTaskSpecToFlatbuffer(TaskSpec task) {
         actorCounter,
         newActorHandlesOffset,
         argsOffset,
-        returnsOffset,
+        numReturnsOffset,
         requiredResourcesOffset,
         requiredPlacementResourcesOffset,
         language,

java/runtime/src/main/java/org/ray/runtime/task/TaskSpec.java

@@ -121,7 +121,7 @@ public TaskSpec(
     this.executionDependencies = new ArrayList<>();
     returnIds = new ObjectId[numReturns];
     for (int i = 0; i < numReturns; ++i) {
-      returnIds[i] = IdUtil.computeReturnId(taskId, i);
+      returnIds[i] = IdUtil.computeReturnId(taskId, i + 1);
     }
   }