mirror of
https://github.com/tiennm99/java-design-patterns.git
synced 2026-05-16 10:59:03 +00:00
refactor: rename queue based load leveling
This commit is contained in:
Ilkka Seppälä
@@ -0,0 +1,117 @@
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/*
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* This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
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*
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* The MIT License
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* Copyright © 2014-2022 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.queue.load.leveling;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.TimeUnit;
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import lombok.extern.slf4j.Slf4j;
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/**
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* Many solutions in the cloud involve running tasks that invoke services. In this environment, if a
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* service is subjected to intermittent heavy loads, it can cause performance or reliability
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* issues.
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*
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* <p>A service could be a component that is part of the same solution as the tasks that utilize
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* it, or it could be a third-party service providing access to frequently used resources such as a
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* cache or a storage service. If the same service is utilized by a number of tasks running
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* concurrently, it can be difficult to predict the volume of requests to which the service might be
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* subjected at any given point in time.
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*
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* <p>We will build a queue-based-load-leveling to solve above problem. Refactor the solution and
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* introduce a queue between the task and the service. The task and the service run asynchronously.
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* The task posts a message containing the data required by the service to a queue. The queue acts
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* as a buffer, storing the message until it is retrieved by the service. The service retrieves the
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* messages from the queue and processes them. Requests from a number of tasks, which can be
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* generated at a highly variable rate, can be passed to the service through the same message
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* queue.
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*
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* <p>The queue effectively decouples the tasks from the service, and the service can handle the
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* messages at its own pace irrespective of the volume of requests from concurrent tasks.
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* Additionally, there is no delay to a task if the service is not available at the time it posts a
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* message to the queue.
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*
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* <p>In this example we have a class {@link MessageQueue} to hold the message {@link Message}
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* objects. All the worker threads {@link TaskGenerator} will submit the messages to the
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* MessageQueue. The service executor class {@link ServiceExecutor} will pick up one task at a time
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* from the Queue and execute them.
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*/
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@Slf4j
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public class App {
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//Executor shut down time limit.
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private static final int SHUTDOWN_TIME = 15;
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/**
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* Program entry point.
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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// An Executor that provides methods to manage termination and methods that can
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// produce a Future for tracking progress of one or more asynchronous tasks.
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ExecutorService executor = null;
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try {
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// Create a MessageQueue object.
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var msgQueue = new MessageQueue();
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LOGGER.info("Submitting TaskGenerators and ServiceExecutor threads.");
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// Create three TaskGenerator threads. Each of them will submit different number of jobs.
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final var taskRunnable1 = new TaskGenerator(msgQueue, 5);
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final var taskRunnable2 = new TaskGenerator(msgQueue, 1);
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final var taskRunnable3 = new TaskGenerator(msgQueue, 2);
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// Create e service which should process the submitted jobs.
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final var srvRunnable = new ServiceExecutor(msgQueue);
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// Create a ThreadPool of 2 threads and
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// submit all Runnable task for execution to executor
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executor = Executors.newFixedThreadPool(2);
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executor.submit(taskRunnable1);
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executor.submit(taskRunnable2);
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executor.submit(taskRunnable3);
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// submitting serviceExecutor thread to the Executor service.
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executor.submit(srvRunnable);
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// Initiates an orderly shutdown.
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LOGGER.info("Initiating shutdown."
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+ " Executor will shutdown only after all the Threads are completed.");
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executor.shutdown();
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// Wait for SHUTDOWN_TIME seconds for all the threads to complete
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// their tasks and then shut down the executor and then exit.
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if (!executor.awaitTermination(SHUTDOWN_TIME, TimeUnit.SECONDS)) {
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LOGGER.info("Executor was shut down and Exiting.");
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executor.shutdownNow();
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}
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} catch (Exception e) {
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LOGGER.error(e.getMessage());
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}
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}
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}
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@@ -0,0 +1,42 @@
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/*
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* This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
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*
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* The MIT License
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* Copyright © 2014-2022 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.queue.load.leveling;
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import lombok.Getter;
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import lombok.RequiredArgsConstructor;
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/**
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* Message class with only one parameter.
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*/
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@Getter
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@RequiredArgsConstructor
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public class Message {
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private final String msg;
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@Override
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public String toString() {
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return msg;
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}
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}
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+71
@@ -0,0 +1,71 @@
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/*
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* This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
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*
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* The MIT License
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* Copyright © 2014-2022 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.queue.load.leveling;
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import java.util.concurrent.ArrayBlockingQueue;
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import java.util.concurrent.BlockingQueue;
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import lombok.extern.slf4j.Slf4j;
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/**
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* MessageQueue class. In this class we will create a Blocking Queue and submit/retrieve all the
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* messages from it.
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*/
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@Slf4j
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public class MessageQueue {
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private final BlockingQueue<Message> blkQueue;
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// Default constructor when called creates Blocking Queue object.
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public MessageQueue() {
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this.blkQueue = new ArrayBlockingQueue<>(1024);
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}
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/**
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* All the TaskGenerator threads will call this method to insert the Messages in to the Blocking
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* Queue.
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*/
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public void submitMsg(Message msg) {
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try {
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if (null != msg) {
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blkQueue.add(msg);
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}
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} catch (Exception e) {
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LOGGER.error(e.getMessage());
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}
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}
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/**
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* All the messages will be retrieved by the ServiceExecutor by calling this method and process
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* them. Retrieves and removes the head of this queue, or returns null if this queue is empty.
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*/
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public Message retrieveMsg() {
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try {
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return blkQueue.poll();
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} catch (Exception e) {
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LOGGER.error(e.getMessage());
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}
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return null;
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}
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}
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+62
@@ -0,0 +1,62 @@
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/*
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* This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
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*
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* The MIT License
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* Copyright © 2014-2022 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.queue.load.leveling;
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import lombok.extern.slf4j.Slf4j;
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/**
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* ServiceExecuotr class. This class will pick up Messages one by one from the Blocking Queue and
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* process them.
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*/
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@Slf4j
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public class ServiceExecutor implements Runnable {
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private final MessageQueue msgQueue;
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public ServiceExecutor(MessageQueue msgQueue) {
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this.msgQueue = msgQueue;
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}
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/**
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* The ServiceExecutor thread will retrieve each message and process it.
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*/
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public void run() {
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try {
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while (!Thread.currentThread().isInterrupted()) {
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var msg = msgQueue.retrieveMsg();
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if (null != msg) {
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LOGGER.info(msg + " is served.");
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} else {
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LOGGER.info("Service Executor: Waiting for Messages to serve .. ");
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}
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Thread.sleep(1000);
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}
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} catch (Exception e) {
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LOGGER.error(e.getMessage());
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}
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}
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}
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@@ -0,0 +1,32 @@
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/*
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* This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
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*
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* The MIT License
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* Copyright © 2014-2022 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
|
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
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* copies of the Software, and to permit persons to whom the Software is
|
||||
* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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||||
*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
||||
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
||||
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.queue.load.leveling;
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/**
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* Task Interface.
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*/
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public interface Task {
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void submit(Message msg);
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}
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+83
@@ -0,0 +1,83 @@
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/*
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* This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
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*
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* The MIT License
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||||
* Copyright © 2014-2022 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
|
||||
* of this software and associated documentation files (the "Software"), to deal
|
||||
* in the Software without restriction, including without limitation the rights
|
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
||||
* copies of the Software, and to permit persons to whom the Software is
|
||||
* furnished to do so, subject to the following conditions:
|
||||
*
|
||||
* The above copyright notice and this permission notice shall be included in
|
||||
* all copies or substantial portions of the Software.
|
||||
*
|
||||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
||||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
||||
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
||||
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
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* THE SOFTWARE.
|
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*/
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package com.iluwatar.queue.load.leveling;
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import lombok.extern.slf4j.Slf4j;
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/**
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* TaskGenerator class. Each TaskGenerator thread will be a Worker which submits messages to the
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* queue. We need to mention the message count for each of the TaskGenerator threads.
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*/
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@Slf4j
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public class TaskGenerator implements Task, Runnable {
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// MessageQueue reference using which we will submit our messages.
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private final MessageQueue msgQueue;
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// Total message count that a TaskGenerator will submit.
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private final int msgCount;
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// Parameterized constructor.
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public TaskGenerator(MessageQueue msgQueue, int msgCount) {
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this.msgQueue = msgQueue;
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this.msgCount = msgCount;
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}
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/**
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* Submit messages to the Blocking Queue.
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*/
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public void submit(Message msg) {
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try {
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this.msgQueue.submitMsg(msg);
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} catch (Exception e) {
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LOGGER.error(e.getMessage());
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}
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}
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/**
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* Each TaskGenerator thread will submit all the messages to the Queue. After every message
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* submission TaskGenerator thread will sleep for 1 second.
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*/
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public void run() {
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var count = this.msgCount;
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try {
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while (count > 0) {
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var statusMsg = "Message-" + count + " submitted by " + Thread.currentThread().getName();
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this.submit(new Message(statusMsg));
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LOGGER.info(statusMsg);
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// reduce the message count.
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count--;
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// Make the current thread to sleep after every Message submission.
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Thread.sleep(1000);
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}
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} catch (Exception e) {
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LOGGER.error(e.getMessage());
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}
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}
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}
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Reference in New Issue
Block a user