org.apache.reef.io.network.NetworkServiceTest.java Source code

Java tutorial

Introduction

Here is the source code for org.apache.reef.io.network.NetworkServiceTest.java

Source

/*
 * 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.reef.io.network;

import org.apache.commons.lang3.StringUtils;
import org.apache.reef.exception.evaluator.NetworkException;
import org.apache.reef.io.network.impl.NetworkService;
import org.apache.reef.io.network.impl.NetworkServiceParameters;
import org.apache.reef.io.network.naming.NameResolver;
import org.apache.reef.io.network.naming.NameResolverConfiguration;
import org.apache.reef.io.network.naming.NameServer;
import org.apache.reef.io.network.naming.NameServerParameters;
import org.apache.reef.io.network.util.StringIdentifierFactory;
import org.apache.reef.io.network.util.Monitor;
import org.apache.reef.io.network.util.StringCodec;
import org.apache.reef.tang.Configuration;
import org.apache.reef.tang.Injector;
import org.apache.reef.tang.Tang;
import org.apache.reef.tang.exceptions.InjectionException;
import org.apache.reef.wake.EventHandler;
import org.apache.reef.wake.Identifier;
import org.apache.reef.wake.IdentifierFactory;
import org.apache.reef.wake.remote.address.LocalAddressProvider;
import org.apache.reef.wake.remote.transport.netty.MessagingTransportFactory;
import org.junit.Assert;
import org.junit.Assume;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TestName;

import java.net.InetSocketAddress;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Network service test.
 */
public class NetworkServiceTest {
    private static final Logger LOG = Logger.getLogger(NetworkServiceTest.class.getName());

    private final LocalAddressProvider localAddressProvider;
    private final String localAddress;

    public NetworkServiceTest() throws InjectionException {
        localAddressProvider = Tang.Factory.getTang().newInjector().getInstance(LocalAddressProvider.class);
        localAddress = localAddressProvider.getLocalAddress();
    }

    @Rule
    public TestName name = new TestName();

    /**
     * NetworkService messaging test.
     */
    @Test
    public void testMessagingNetworkService() throws Exception {
        LOG.log(Level.FINEST, name.getMethodName());

        final IdentifierFactory factory = new StringIdentifierFactory();

        final Injector injector = Tang.Factory.getTang().newInjector();
        injector.bindVolatileParameter(NameServerParameters.NameServerIdentifierFactory.class, factory);
        injector.bindVolatileInstance(LocalAddressProvider.class, this.localAddressProvider);

        try (final NameServer server = injector.getInstance(NameServer.class)) {
            final int nameServerPort = server.getPort();

            final int numMessages = 10;
            final Monitor monitor = new Monitor();

            // network service
            final String name2 = "task2";
            final String name1 = "task1";
            final Configuration nameResolverConf = Tang.Factory.getTang()
                    .newConfigurationBuilder(NameResolverConfiguration.CONF
                            .set(NameResolverConfiguration.NAME_SERVER_HOSTNAME, this.localAddress)
                            .set(NameResolverConfiguration.NAME_SERVICE_PORT, nameServerPort).build())
                    .build();

            final Injector injector2 = Tang.Factory.getTang().newInjector(nameResolverConf);

            LOG.log(Level.FINEST, "=== Test network service receiver start");
            LOG.log(Level.FINEST, "=== Test network service sender start");
            try (final NameResolver nameResolver = injector2.getInstance(NameResolver.class)) {
                injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceIdentifierFactory.class,
                        factory);
                injector2.bindVolatileInstance(NameResolver.class, nameResolver);
                injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceCodec.class,
                        new StringCodec());
                injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceTransportFactory.class,
                        injector.getInstance(MessagingTransportFactory.class));
                injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceExceptionHandler.class,
                        new ExceptionHandler());

                final Injector injectorNs2 = injector2.forkInjector();
                injectorNs2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                        new MessageHandler<String>(name2, monitor, numMessages));
                final NetworkService<String> ns2 = injectorNs2.getInstance(NetworkService.class);

                final Injector injectorNs1 = injector2.forkInjector();
                injectorNs1.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                        new MessageHandler<String>(name1, null, 0));
                final NetworkService<String> ns1 = injectorNs1.getInstance(NetworkService.class);

                ns2.registerId(factory.getNewInstance(name2));
                final int port2 = ns2.getTransport().getListeningPort();
                server.register(factory.getNewInstance("task2"), new InetSocketAddress(this.localAddress, port2));

                ns1.registerId(factory.getNewInstance(name1));
                final int port1 = ns1.getTransport().getListeningPort();
                server.register(factory.getNewInstance("task1"), new InetSocketAddress(this.localAddress, port1));

                final Identifier destId = factory.getNewInstance(name2);

                try (final Connection<String> conn = ns1.newConnection(destId)) {
                    conn.open();
                    for (int count = 0; count < numMessages; ++count) {
                        conn.write("hello! " + count);
                    }
                    monitor.mwait();

                } catch (final NetworkException e) {
                    e.printStackTrace();
                    throw new RuntimeException(e);
                }
            }
        }
    }

    /**
     * NetworkService messaging rate benchmark.
     */
    @Test
    public void testMessagingNetworkServiceRate() throws Exception {

        Assume.assumeFalse("Use log level INFO to run benchmarking", LOG.isLoggable(Level.FINEST));

        LOG.log(Level.FINEST, name.getMethodName());

        final IdentifierFactory factory = new StringIdentifierFactory();

        final Injector injector = Tang.Factory.getTang().newInjector();
        injector.bindVolatileParameter(NameServerParameters.NameServerIdentifierFactory.class, factory);
        injector.bindVolatileInstance(LocalAddressProvider.class, this.localAddressProvider);

        try (final NameServer server = injector.getInstance(NameServer.class)) {
            final int nameServerPort = server.getPort();

            final int[] messageSizes = { 1, 16, 32, 64, 512, 64 * 1024, 1024 * 1024 };

            for (final int size : messageSizes) {
                final int numMessages = 300000 / (Math.max(1, size / 512));
                final Monitor monitor = new Monitor();

                // network service
                final String name2 = "task2";
                final String name1 = "task1";
                final Configuration nameResolverConf = Tang.Factory.getTang()
                        .newConfigurationBuilder(NameResolverConfiguration.CONF
                                .set(NameResolverConfiguration.NAME_SERVER_HOSTNAME, this.localAddress)
                                .set(NameResolverConfiguration.NAME_SERVICE_PORT, nameServerPort).build())
                        .build();

                final Injector injector2 = Tang.Factory.getTang().newInjector(nameResolverConf);

                LOG.log(Level.FINEST, "=== Test network service receiver start");
                LOG.log(Level.FINEST, "=== Test network service sender start");
                try (final NameResolver nameResolver = injector2.getInstance(NameResolver.class)) {
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceIdentifierFactory.class,
                            factory);
                    injector2.bindVolatileInstance(NameResolver.class, nameResolver);
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceCodec.class,
                            new StringCodec());
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceTransportFactory.class,
                            injector.getInstance(MessagingTransportFactory.class));
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceExceptionHandler.class,
                            new ExceptionHandler());

                    final Injector injectorNs2 = injector2.forkInjector();
                    injectorNs2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                            new MessageHandler<String>(name2, monitor, numMessages));
                    final NetworkService<String> ns2 = injectorNs2.getInstance(NetworkService.class);

                    final Injector injectorNs1 = injector2.forkInjector();
                    injectorNs1.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                            new MessageHandler<String>(name1, null, 0));
                    final NetworkService<String> ns1 = injectorNs1.getInstance(NetworkService.class);

                    ns2.registerId(factory.getNewInstance(name2));
                    final int port2 = ns2.getTransport().getListeningPort();
                    server.register(factory.getNewInstance("task2"),
                            new InetSocketAddress(this.localAddress, port2));

                    ns1.registerId(factory.getNewInstance(name1));
                    final int port1 = ns1.getTransport().getListeningPort();
                    server.register(factory.getNewInstance("task1"),
                            new InetSocketAddress(this.localAddress, port1));

                    final Identifier destId = factory.getNewInstance(name2);
                    final String message = StringUtils.repeat('1', size);

                    final long start = System.currentTimeMillis();
                    try (Connection<String> conn = ns1.newConnection(destId)) {
                        conn.open();
                        for (int i = 0; i < numMessages; i++) {
                            conn.write(message);
                        }
                        monitor.mwait();
                    } catch (final NetworkException e) {
                        e.printStackTrace();
                        throw new RuntimeException(e);
                    }
                    final long end = System.currentTimeMillis();
                    final double runtime = ((double) end - start) / 1000;
                    LOG.log(Level.FINEST, "size: " + size + "; messages/s: " + numMessages / runtime
                            + " bandwidth(bytes/s): " + ((double) numMessages * 2 * size) / runtime); // x2 for unicode chars
                }
            }
        }
    }

    /**
     * NetworkService messaging rate benchmark.
     */
    @Test
    public void testMessagingNetworkServiceRateDisjoint() throws Exception {

        Assume.assumeFalse("Use log level INFO to run benchmarking", LOG.isLoggable(Level.FINEST));

        LOG.log(Level.FINEST, name.getMethodName());

        final IdentifierFactory factory = new StringIdentifierFactory();

        final Injector injector = Tang.Factory.getTang().newInjector();
        injector.bindVolatileParameter(NameServerParameters.NameServerIdentifierFactory.class, factory);
        injector.bindVolatileInstance(LocalAddressProvider.class, this.localAddressProvider);

        try (final NameServer server = injector.getInstance(NameServer.class)) {
            final int nameServerPort = server.getPort();

            final BlockingQueue<Object> barrier = new LinkedBlockingQueue<>();

            final int numThreads = 4;
            final int size = 2000;
            final int numMessages = 300000 / (Math.max(1, size / 512));
            final int totalNumMessages = numMessages * numThreads;

            final ExecutorService e = Executors.newCachedThreadPool();
            for (int t = 0; t < numThreads; t++) {
                final int tt = t;

                e.submit(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            final Monitor monitor = new Monitor();

                            // network service
                            final String name2 = "task2-" + tt;
                            final String name1 = "task1-" + tt;
                            final Configuration nameResolverConf = Tang.Factory.getTang()
                                    .newConfigurationBuilder(NameResolverConfiguration.CONF
                                            .set(NameResolverConfiguration.NAME_SERVER_HOSTNAME, localAddress)
                                            .set(NameResolverConfiguration.NAME_SERVICE_PORT, nameServerPort)
                                            .build())
                                    .build();

                            final Injector injector = Tang.Factory.getTang().newInjector(nameResolverConf);

                            LOG.log(Level.FINEST, "=== Test network service receiver start");
                            LOG.log(Level.FINEST, "=== Test network service sender start");
                            try (final NameResolver nameResolver = injector.getInstance(NameResolver.class)) {
                                injector.bindVolatileParameter(
                                        NetworkServiceParameters.NetworkServiceIdentifierFactory.class, factory);
                                injector.bindVolatileInstance(NameResolver.class, nameResolver);
                                injector.bindVolatileParameter(NetworkServiceParameters.NetworkServiceCodec.class,
                                        new StringCodec());
                                injector.bindVolatileParameter(
                                        NetworkServiceParameters.NetworkServiceTransportFactory.class,
                                        injector.getInstance(MessagingTransportFactory.class));
                                injector.bindVolatileParameter(
                                        NetworkServiceParameters.NetworkServiceExceptionHandler.class,
                                        new ExceptionHandler());

                                final Injector injectorNs2 = injector.forkInjector();
                                injectorNs2.bindVolatileParameter(
                                        NetworkServiceParameters.NetworkServiceHandler.class,
                                        new MessageHandler<String>(name2, monitor, numMessages));
                                final NetworkService<String> ns2 = injectorNs2.getInstance(NetworkService.class);

                                final Injector injectorNs1 = injector.forkInjector();
                                injectorNs1.bindVolatileParameter(
                                        NetworkServiceParameters.NetworkServiceHandler.class,
                                        new MessageHandler<String>(name1, null, 0));
                                final NetworkService<String> ns1 = injectorNs1.getInstance(NetworkService.class);

                                ns2.registerId(factory.getNewInstance(name2));
                                final int port2 = ns2.getTransport().getListeningPort();
                                server.register(factory.getNewInstance(name2),
                                        new InetSocketAddress(localAddress, port2));

                                ns1.registerId(factory.getNewInstance(name1));
                                final int port1 = ns1.getTransport().getListeningPort();
                                server.register(factory.getNewInstance(name1),
                                        new InetSocketAddress(localAddress, port1));

                                final Identifier destId = factory.getNewInstance(name2);
                                final String message = StringUtils.repeat('1', size);

                                try (Connection<String> conn = ns1.newConnection(destId)) {
                                    conn.open();
                                    for (int i = 0; i < numMessages; i++) {
                                        conn.write(message);
                                    }
                                    monitor.mwait();
                                } catch (final NetworkException e) {
                                    e.printStackTrace();
                                    throw new RuntimeException(e);
                                }
                            }
                        } catch (final Exception e) {
                            e.printStackTrace();
                            throw new RuntimeException(e);
                        }
                    }
                });
            }

            // start and time
            final long start = System.currentTimeMillis();
            final Object ignore = new Object();
            for (int i = 0; i < numThreads; i++) {
                barrier.add(ignore);
            }
            e.shutdown();
            e.awaitTermination(100, TimeUnit.SECONDS);
            final long end = System.currentTimeMillis();

            final double runtime = ((double) end - start) / 1000;
            LOG.log(Level.FINEST, "size: " + size + "; messages/s: " + totalNumMessages / runtime
                    + " bandwidth(bytes/s): " + ((double) totalNumMessages * 2 * size) / runtime); // x2 for unicode chars
        }
    }

    @Test
    public void testMultithreadedSharedConnMessagingNetworkServiceRate() throws Exception {

        Assume.assumeFalse("Use log level INFO to run benchmarking", LOG.isLoggable(Level.FINEST));

        LOG.log(Level.FINEST, name.getMethodName());

        final IdentifierFactory factory = new StringIdentifierFactory();

        final Injector injector = Tang.Factory.getTang().newInjector();
        injector.bindVolatileParameter(NameServerParameters.NameServerIdentifierFactory.class, factory);
        injector.bindVolatileInstance(LocalAddressProvider.class, this.localAddressProvider);
        try (final NameServer server = injector.getInstance(NameServer.class)) {
            final int nameServerPort = server.getPort();

            final int[] messageSizes = { 2000 }; // {1,16,32,64,512,64*1024,1024*1024};

            for (final int size : messageSizes) {
                final int numMessages = 300000 / (Math.max(1, size / 512));
                final int numThreads = 2;
                final int totalNumMessages = numMessages * numThreads;
                final Monitor monitor = new Monitor();

                // network service
                final String name2 = "task2";
                final String name1 = "task1";
                final Configuration nameResolverConf = Tang.Factory.getTang()
                        .newConfigurationBuilder(NameResolverConfiguration.CONF
                                .set(NameResolverConfiguration.NAME_SERVER_HOSTNAME, this.localAddress)
                                .set(NameResolverConfiguration.NAME_SERVICE_PORT, nameServerPort).build())
                        .build();

                final Injector injector2 = Tang.Factory.getTang().newInjector(nameResolverConf);

                LOG.log(Level.FINEST, "=== Test network service receiver start");
                LOG.log(Level.FINEST, "=== Test network service sender start");
                try (final NameResolver nameResolver = injector2.getInstance(NameResolver.class)) {
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceIdentifierFactory.class,
                            factory);
                    injector2.bindVolatileInstance(NameResolver.class, nameResolver);
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceCodec.class,
                            new StringCodec());
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceTransportFactory.class,
                            injector.getInstance(MessagingTransportFactory.class));
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceExceptionHandler.class,
                            new ExceptionHandler());

                    final Injector injectorNs2 = injector2.forkInjector();
                    injectorNs2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                            new MessageHandler<String>(name2, monitor, totalNumMessages));
                    final NetworkService<String> ns2 = injectorNs2.getInstance(NetworkService.class);

                    final Injector injectorNs1 = injector2.forkInjector();
                    injectorNs1.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                            new MessageHandler<String>(name1, null, 0));
                    final NetworkService<String> ns1 = injectorNs1.getInstance(NetworkService.class);

                    ns2.registerId(factory.getNewInstance(name2));
                    final int port2 = ns2.getTransport().getListeningPort();
                    server.register(factory.getNewInstance("task2"),
                            new InetSocketAddress(this.localAddress, port2));

                    ns1.registerId(factory.getNewInstance(name1));
                    final int port1 = ns1.getTransport().getListeningPort();
                    server.register(factory.getNewInstance("task1"),
                            new InetSocketAddress(this.localAddress, port1));

                    final Identifier destId = factory.getNewInstance(name2);

                    try (final Connection<String> conn = ns1.newConnection(destId)) {
                        conn.open();

                        final String message = StringUtils.repeat('1', size);
                        final ExecutorService e = Executors.newCachedThreadPool();

                        final long start = System.currentTimeMillis();
                        for (int i = 0; i < numThreads; i++) {
                            e.submit(new Runnable() {

                                @Override
                                public void run() {
                                    for (int i = 0; i < numMessages; i++) {
                                        conn.write(message);
                                    }
                                }
                            });
                        }

                        e.shutdown();
                        e.awaitTermination(30, TimeUnit.SECONDS);
                        monitor.mwait();

                        final long end = System.currentTimeMillis();
                        final double runtime = ((double) end - start) / 1000;

                        LOG.log(Level.FINEST, "size: " + size + "; messages/s: " + totalNumMessages / runtime
                                + " bandwidth(bytes/s): " + ((double) totalNumMessages * 2 * size) / runtime); // x2 for unicode chars
                    }
                }
            }
        }
    }

    /**
     * NetworkService messaging rate benchmark.
     */
    @Test
    public void testMessagingNetworkServiceBatchingRate() throws Exception {

        Assume.assumeFalse("Use log level INFO to run benchmarking", LOG.isLoggable(Level.FINEST));

        LOG.log(Level.FINEST, name.getMethodName());

        final IdentifierFactory factory = new StringIdentifierFactory();

        final Injector injector = Tang.Factory.getTang().newInjector();
        injector.bindVolatileParameter(NameServerParameters.NameServerIdentifierFactory.class, factory);
        injector.bindVolatileInstance(LocalAddressProvider.class, this.localAddressProvider);

        try (final NameServer server = injector.getInstance(NameServer.class)) {
            final int nameServerPort = server.getPort();

            final int batchSize = 1024 * 1024;
            final int[] messageSizes = { 32, 64, 512 };

            for (final int size : messageSizes) {
                final int numMessages = 300 / (Math.max(1, size / 512));
                final Monitor monitor = new Monitor();

                // network service
                final String name2 = "task2";
                final String name1 = "task1";
                final Configuration nameResolverConf = Tang.Factory.getTang()
                        .newConfigurationBuilder(NameResolverConfiguration.CONF
                                .set(NameResolverConfiguration.NAME_SERVER_HOSTNAME, this.localAddress)
                                .set(NameResolverConfiguration.NAME_SERVICE_PORT, nameServerPort).build())
                        .build();

                final Injector injector2 = Tang.Factory.getTang().newInjector(nameResolverConf);

                LOG.log(Level.FINEST, "=== Test network service receiver start");
                LOG.log(Level.FINEST, "=== Test network service sender start");
                try (final NameResolver nameResolver = injector2.getInstance(NameResolver.class)) {
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceIdentifierFactory.class,
                            factory);
                    injector2.bindVolatileInstance(NameResolver.class, nameResolver);
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceCodec.class,
                            new StringCodec());
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceTransportFactory.class,
                            injector.getInstance(MessagingTransportFactory.class));
                    injector2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceExceptionHandler.class,
                            new ExceptionHandler());

                    final Injector injectorNs2 = injector2.forkInjector();
                    injectorNs2.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                            new MessageHandler<String>(name2, monitor, numMessages));
                    final NetworkService<String> ns2 = injectorNs2.getInstance(NetworkService.class);

                    final Injector injectorNs1 = injector2.forkInjector();
                    injectorNs1.bindVolatileParameter(NetworkServiceParameters.NetworkServiceHandler.class,
                            new MessageHandler<String>(name1, null, 0));
                    final NetworkService<String> ns1 = injectorNs1.getInstance(NetworkService.class);

                    ns2.registerId(factory.getNewInstance(name2));
                    final int port2 = ns2.getTransport().getListeningPort();
                    server.register(factory.getNewInstance("task2"),
                            new InetSocketAddress(this.localAddress, port2));

                    ns1.registerId(factory.getNewInstance(name1));
                    final int port1 = ns1.getTransport().getListeningPort();
                    server.register(factory.getNewInstance("task1"),
                            new InetSocketAddress(this.localAddress, port1));

                    final Identifier destId = factory.getNewInstance(name2);
                    final String message = StringUtils.repeat('1', batchSize);

                    final long start = System.currentTimeMillis();
                    try (Connection<String> conn = ns1.newConnection(destId)) {
                        conn.open();
                        for (int i = 0; i < numMessages; i++) {
                            conn.write(message);
                        }
                        monitor.mwait();
                    } catch (final NetworkException e) {
                        e.printStackTrace();
                        throw new RuntimeException(e);
                    }
                    final long end = System.currentTimeMillis();
                    final double runtime = ((double) end - start) / 1000;
                    final long numAppMessages = numMessages * batchSize / size;
                    LOG.log(Level.FINEST, "size: " + size + "; messages/s: " + numAppMessages / runtime
                            + " bandwidth(bytes/s): " + ((double) numAppMessages * 2 * size) / runtime); // x2 for unicode chars
                }
            }
        }
    }

    /**
     * Test message handler.
     */
    class MessageHandler<T> implements EventHandler<Message<T>> {

        private final String name;
        private final int expected;
        private final Monitor monitor;
        private final AtomicInteger count = new AtomicInteger(0);

        MessageHandler(final String name, final Monitor monitor, final int expected) {
            this.name = name;
            this.monitor = monitor;
            this.expected = expected;
        }

        @Override
        public void onNext(final Message<T> value) {

            final int currentCount = count.incrementAndGet();

            LOG.log(Level.FINER, "{0} Message {1}/{2} :: {3}",
                    new Object[] { name, currentCount, expected, value });

            Assert.assertTrue(currentCount <= expected);

            if (currentCount >= expected) {
                monitor.mnotify();
            }
        }
    }

    /**
     * Test exception handler.
     */
    class ExceptionHandler implements EventHandler<Exception> {
        @Override
        public void onNext(final Exception error) {
            System.err.println(error);
        }
    }
}