Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/938#discussion_r137939116
--- Diff:
common/src/main/java/org/apache/drill/common/exceptions/RetryAfterSpillException.java
---
@@ -0,0 +1,32 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.common.exceptions;
+
+import org.apache.drill.exec.proto.UserBitShared;
+
+/**
+ * A special exception to be caught by caller, who is supposed to free
memory by spilling and try again
+ *
+ */
+public class RetryAfterSpillException extends UserException {
--- End diff --
If this exception is thrown and caught internally, it should not extend
`UserException`. Instead it should extend the Java `RuntimeException`.
Better, since you know you must catch this, this should be a checked
exception, extended from `Exception` and declared by the method that throws it.
`UserException` is purely for exceptions reported to the user.
---
