| /* |
| * 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.samza.monitor; |
| |
| /** |
| * A Monitor is a class implementing some functionality that should be done every N milliseconds on a YARN RM or NM. |
| * Classes specified in the config will have their monitor() method called at a configurable interval. |
| * For example, one could implement a Monitor that checks for leaked containers and kills them, ensuring that |
| * no leaked container survives on a NodeManager host for more than N ms (where N is the monitor run interval.) |
| * |
| * Implementations can override .toString() for better logging. |
| */ |
| public interface Monitor { |
| |
| /** |
| * Do the work of the monitor. Because this can be arbitrary behavior up to and including script execution, |
| * IPC-related IOExceptions and concurrency-related InterruptedExceptions are caught by the SamzaMonitorService. |
| * @throws Exception if there was any problem running the monitor. |
| */ |
| void monitor() throws Exception; |
| } |
