| /** |
| * 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.hadoop.util; |
| |
| import sun.misc.Signal; |
| import sun.misc.SignalHandler; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * This class logs a message whenever we're about to exit on a UNIX signal. |
| * This is helpful for determining the root cause of a process' exit. |
| * For example, if the process exited because the system administrator |
| * ran a standard "kill," you would see 'EXITING ON SIGNAL SIGTERM' in the log. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public enum SignalLogger { |
| INSTANCE; |
| |
| private boolean registered = false; |
| |
| /** |
| * Our signal handler. |
| */ |
| private static class Handler implements SignalHandler { |
| final private LogAdapter LOG; |
| final private SignalHandler prevHandler; |
| |
| Handler(String name, LogAdapter LOG) { |
| this.LOG = LOG; |
| prevHandler = Signal.handle(new Signal(name), this); |
| } |
| |
| /** |
| * Handle an incoming signal. |
| * |
| * @param signal The incoming signal |
| */ |
| @Override |
| public void handle(Signal signal) { |
| LOG.error("RECEIVED SIGNAL " + signal.getNumber() + |
| ": SIG" + signal.getName()); |
| prevHandler.handle(signal); |
| } |
| } |
| |
| /** |
| * Register some signal handlers. |
| * |
| * @param LOG The log4j logfile to use in the signal handlers. |
| */ |
| public void register(final Log LOG) { |
| register(LogAdapter.create(LOG)); |
| } |
| |
| void register(final LogAdapter LOG) { |
| if (registered) { |
| throw new IllegalStateException("Can't re-install the signal handlers."); |
| } |
| registered = true; |
| StringBuilder bld = new StringBuilder(); |
| bld.append("registered UNIX signal handlers for ["); |
| final String SIGNALS[] = { "TERM", "HUP", "INT" }; |
| String separator = ""; |
| for (String signalName : SIGNALS) { |
| try { |
| new Handler(signalName, LOG); |
| bld.append(separator); |
| bld.append(signalName); |
| separator = ", "; |
| } catch (Exception e) { |
| LOG.debug(e); |
| } |
| } |
| bld.append("]"); |
| LOG.info(bld.toString()); |
| } |
| } |