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Merge pull request #1235 from mattrjacobs/hystrix-examples-async
Add demo that composes async command executions
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‎hystrix-examples/src/main/java/com/netflix/hystrix/examples/demo/HystrixCommandAsyncDemo.java

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/**
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* Copyright 2012 Netflix, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.netflix.hystrix.examples.demo;
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import java.math.BigDecimal;
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import java.net.HttpCookie;
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import java.util.Random;
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import com.netflix.config.ConfigurationManager;
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import com.netflix.hystrix.HystrixCommandKey;
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import com.netflix.hystrix.HystrixCommandMetrics;
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import com.netflix.hystrix.HystrixCommandMetrics.HealthCounts;
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import com.netflix.hystrix.HystrixRequestLog;
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import com.netflix.hystrix.strategy.concurrency.HystrixRequestContext;
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import rx.Observable;
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import rx.functions.Action0;
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import rx.functions.Action1;
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import rx.functions.Func1;
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import rx.functions.Func2;
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/**
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* Executable client that demonstrates the lifecycle, metrics, request log and behavior of HystrixCommands.
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*/
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public class HystrixCommandAsyncDemo {
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// public static void main(String args[]) {
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// new HystrixCommandAsyncDemo().startDemo(true);
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// }
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public HystrixCommandAsyncDemo() {
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/*
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* Instead of using injected properties we'll set them via Archaius
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* so the rest of the code behaves as it would in a real system
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* where it picks up properties externally provided.
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*/
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ConfigurationManager.getConfigInstance().setProperty("hystrix.threadpool.default.coreSize", 8);
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ConfigurationManager.getConfigInstance().setProperty("hystrix.command.CreditCardCommand.execution.isolation.thread.timeoutInMilliseconds", 3000);
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ConfigurationManager.getConfigInstance().setProperty("hystrix.command.GetUserAccountCommand.execution.isolation.thread.timeoutInMilliseconds", 50);
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// set the rolling percentile more granular so we see data change every second rather than every 10 seconds as is the default
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ConfigurationManager.getConfigInstance().setProperty("hystrix.command.default.metrics.rollingPercentile.numBuckets", 60);
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}
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public void startDemo(boolean shouldLog) {
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startMetricsMonitor(shouldLog);
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while (true) {
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Observable<CreditCardAuthorizationResult> o = runSimulatedRequestOnCallerThread(shouldLog);
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o.subscribe();
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try {
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Thread.sleep(400);
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} catch (InterruptedException ex) {
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ex.printStackTrace();
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}
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}
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}
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private final static Random r = new Random();
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private Observable<CreditCardAuthorizationResult> runSimulatedRequestOnCallerThread(final boolean shouldLog) {
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final HystrixRequestContext context = HystrixRequestContext.initializeContext();
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//System.out.println("Map at start : " + map.get() + " : " + Thread.currentThread().getName());
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return observeSimulatedUserRequestForOrderConfirmationAndCreditCardPayment()
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.doOnUnsubscribe(new Action0() {
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@Override
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public void call() {
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if (shouldLog) {
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System.out.println("Request => " + HystrixRequestLog.getCurrentRequest().getExecutedCommandsAsString());
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}
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context.shutdown();
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}
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})
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.doOnError(new Action1<Throwable>() {
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@Override
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public void call(Throwable throwable) {
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throwable.printStackTrace();
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}
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});
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}
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private class Pair<A, B> {
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private final A a;
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private final B b;
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Pair(A a, B b) {
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this.a = a;
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this.b = b;
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}
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A a() {
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return this.a;
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}
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B b() {
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return this.b;
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}
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}
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public Observable<CreditCardAuthorizationResult> observeSimulatedUserRequestForOrderConfirmationAndCreditCardPayment() {
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/* fetch user object with http cookies */
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Observable<UserAccount> user = new GetUserAccountCommand(new HttpCookie("mockKey", "mockValueFromHttpRequest")).observe();
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/* fetch the payment information (asynchronously) for the user so the credit card payment can proceed */
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Observable<PaymentInformation> paymentInformation = user.flatMap(new Func1<UserAccount, Observable<PaymentInformation>>() {
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@Override
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public Observable<PaymentInformation> call(UserAccount userAccount) {
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return new GetPaymentInformationCommand(userAccount).observe();
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}
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});
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/* fetch the order we're processing for the user */
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int orderIdFromRequestArgument = 13579;
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final Observable<Order> previouslySavedOrder = new GetOrderCommand(orderIdFromRequestArgument).observe();
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return Observable.zip(paymentInformation, previouslySavedOrder, new Func2<PaymentInformation, Order, Pair<PaymentInformation, Order>>() {
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@Override
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public Pair<PaymentInformation, Order> call(PaymentInformation paymentInformation, Order order) {
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return new Pair<PaymentInformation, Order>(paymentInformation, order);
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}
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}).flatMap(new Func1<Pair<PaymentInformation, Order>, Observable<CreditCardAuthorizationResult>>() {
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@Override
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public Observable<CreditCardAuthorizationResult> call(Pair<PaymentInformation, Order> pair) {
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return new CreditCardCommand(pair.b(), pair.a(), new BigDecimal(123.45)).observe();
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}
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});
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}
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public void startMetricsMonitor(final boolean shouldLog) {
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Thread t = new Thread(new Runnable() {
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@Override
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public void run() {
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while (true) {
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/**
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* Since this is a simple example and we know the exact HystrixCommandKeys we are interested in
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* we will retrieve the HystrixCommandMetrics objects directly.
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*
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* Typically you would instead retrieve metrics from where they are published which is by default
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* done using Servo: https://github.com/Netflix/Hystrix/wiki/Metrics-and-Monitoring
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*/
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// wait 5 seconds on each loop
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try {
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Thread.sleep(5000);
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} catch (Exception e) {
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// ignore
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}
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// we are using default names so can use class.getSimpleName() to derive the keys
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HystrixCommandMetrics creditCardMetrics = HystrixCommandMetrics.getInstance(HystrixCommandKey.Factory.asKey(CreditCardCommand.class.getSimpleName()));
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HystrixCommandMetrics orderMetrics = HystrixCommandMetrics.getInstance(HystrixCommandKey.Factory.asKey(GetOrderCommand.class.getSimpleName()));
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HystrixCommandMetrics userAccountMetrics = HystrixCommandMetrics.getInstance(HystrixCommandKey.Factory.asKey(GetUserAccountCommand.class.getSimpleName()));
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HystrixCommandMetrics paymentInformationMetrics = HystrixCommandMetrics.getInstance(HystrixCommandKey.Factory.asKey(GetPaymentInformationCommand.class.getSimpleName()));
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if (shouldLog) {
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// print out metrics
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StringBuilder out = new StringBuilder();
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out.append("\n");
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out.append("#####################################################################################").append("\n");
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out.append("# CreditCardCommand: " + getStatsStringFromMetrics(creditCardMetrics)).append("\n");
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out.append("# GetOrderCommand: " + getStatsStringFromMetrics(orderMetrics)).append("\n");
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out.append("# GetUserAccountCommand: " + getStatsStringFromMetrics(userAccountMetrics)).append("\n");
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out.append("# GetPaymentInformationCommand: " + getStatsStringFromMetrics(paymentInformationMetrics)).append("\n");
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out.append("#####################################################################################").append("\n");
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System.out.println(out.toString());
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}
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}
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}
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private String getStatsStringFromMetrics(HystrixCommandMetrics metrics) {
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StringBuilder m = new StringBuilder();
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if (metrics != null) {
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HealthCounts health = metrics.getHealthCounts();
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m.append("Requests: ").append(health.getTotalRequests()).append(" ");
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m.append("Errors: ").append(health.getErrorCount()).append(" (").append(health.getErrorPercentage()).append("%) ");
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m.append("Mean: ").append(metrics.getExecutionTimePercentile(50)).append(" ");
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m.append("75th: ").append(metrics.getExecutionTimePercentile(75)).append(" ");
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m.append("90th: ").append(metrics.getExecutionTimePercentile(90)).append(" ");
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m.append("99th: ").append(metrics.getExecutionTimePercentile(99)).append(" ");
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}
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return m.toString();
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}
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});
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t.setDaemon(true);
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t.start();
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}
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}

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