add loopcount

src/edu/washington/escience/myria/api/encoding/QueryConstruct.java

@@ -89,8 +89,13 @@ public static Map<Integer, SubQueryPlan> instantiate(final List<PlanFragmentEnco
     for (PlanFragmentEncoding fragment : fragments) {
       instantiateFragmentOperators(fragment, args, allOperators);
     }
-    while (setConsumerSchema(fragments, allOperators)) {
-      /* Do it iteratively until no new consumer has its schema to be set. */
+    int loopCount = 0;
+    while (setConsumerSchema(fragments, allOperators) && loopCount++ < allOperators.size()) {
+      /*
+       * Do it iteratively until no new consumer has its schema to be set. Add a loop count to prevent us from having an
+       * infinite loop (which should NOT happen). Since each iteration should set the schema of at least one consumer,
+       * setting the threshold to be the number of operators is enough.
+       */
     }
     Map<Integer, SubQueryPlan> plan = Maps.newHashMap();
     for (PlanFragmentEncoding fragment : fragments) {