GlobalUncaughtExceptionHandler.java

/*
 * Copyright (C) 2014 Indeed Inc.
 *
 * Licensed 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 com.indeed.imhotep.web;

/**
 * @author vladimir
 */

public class GlobalUncaughtExceptionHandler implements Thread.UncaughtExceptionHandler {
    static final int RETURN_CODE = 2;
    static final int SHUTDOWN_ALLOW_TIME = 60000;   // allow 1 minute to cleanly exit

    public void uncaughtException(Thread t, Throwable e) {
        if(e instanceof OutOfMemoryError) {
            try {
                System.err.println("Out Of Memory encountered in a non Query Servlet thread. Can't recover.");
                e.printStackTrace(System.err);
            } catch (Throwable ignored)  {}

            terminate(RETURN_CODE, SHUTDOWN_ALLOW_TIME);
        }
    }

    public static void terminate(int returnCode, final int shutdownTimeoutMS) {
        try {
            ExitThread exitThread = new ExitThread(returnCode);
            exitThread.start();
            exitThread.join(shutdownTimeoutMS);
            if (!exitThread.finished) {
                try {
                    System.err.println("Shutdown timed out. Force halting VM");
                } finally {
                    Runtime.getRuntime().halt(returnCode);  // we couldn't shut down in time. force stop
                }
            }

        } catch (Throwable ignored) {
            try {
                System.err.println("Error during shut down. Force halting VM");
            } finally {
                Runtime.getRuntime().halt(returnCode); // we had a problem during orderly shutdown. force stop
            }
        }
    }

    private static class ExitThread extends Thread {
        final int returnCode;
        boolean finished = false;

        private ExitThread(int returnCode) {
            this.returnCode = returnCode;
        }

        public void run() {
            System.exit(returnCode);
            finished = true;
            System.err.println("Completed orderly shut down");  // this doesn't actually get printed
        }
    }

    /**
     * Registers itself as the default uncaught exception handler
     */
    public static void register() {
        Thread.setDefaultUncaughtExceptionHandler(new GlobalUncaughtExceptionHandler());
    }
}