本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 透過 Amazon SQS 使用水平擴展和動作批次來增加輸送量
<a name="sqs-throughput-horizontal-scaling-and-batching"></a>

Amazon SQS 支援高輸送量傳訊。如需輸送量限制的詳細資訊，請參閱 [Amazon SQS 訊息配額](quotas-messages.md)。

若要最大化輸送量：
+ 透過新增更多每個 的執行個體，水平[擴展](#horizontal-scaling)生產者和消費者。
+ 使用[動作批次](#request-batching)在單一請求中傳送或接收多則訊息，減少 API 呼叫額外負荷。

## 水平擴展
<a name="horizontal-scaling"></a>

由於您是透過 HTTP 請求-回應協定來存取 Amazon SQS，*請求延遲* (自開始請求至收到回應的時間間隔) 會限制您透過單一連線使用單一執行緒所能達到的輸送量。例如，若 Amazon EC2 型的用戶端到 Amazon SQS 的延遲度在相同區域的平均值為 20 毫秒，透過單一連線使用單一執行緒可達到的最大輸送量平均為 50 TPS。

*水平擴展*意指增加訊息生產者 (提出 `[SendMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessage.html)` 請求) 及消費者 (提出 `[ReceiveMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ReceiveMessage.html)` 和 `[DeleteMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_DeleteMessage.html)` 請求) 的數目，藉以提高佇列整體的傳輸量。水平擴展的方式有三種：
+ 增加每個用戶端的執行緒數目
+ 增加更多用戶端
+ 增加每個用戶端的執行緒數目並增加更多用戶端

增加更多用戶端之後，基本上佇列傳輸量會獲得線性增益。例如，若用戶端數目加倍，傳輸量也會翻倍。

## 動作批次處理
<a name="request-batching"></a>

*批次處理*可在每次往返服務期間處理更多工作 (例如，透過單次 `SendMessageBatch` 請求傳送多則訊息)。Amazon SQS 批次動作包括 `[SendMessageBatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessageBatch.html)`、`[DeleteMessageBatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_DeleteMessageBatch.html)` 和 `[ChangeMessageVisibilityBatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ChangeMessageVisibilityBatch.html)`。若要在不變動生產者或消費者的情況下利用批次處理功能，您可以使用 [Amazon SQS 緩衝非同步用戶端](sqs-client-side-buffering-request-batching.md)。

**注意**  
由於 `[ReceiveMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ReceiveMessage.html)` 一次可處理 10 則訊息，也就不必有 `ReceiveMessageBatch` 動作。

批次處理會將批次動作的延遲度分散到批次請求中的多則訊息，而非接受單則訊息 (例如 `[SendMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessage.html)` 請求) 的所有延遲。由於每次往返所執行的工作較多，批次請求可以有效率地運用執行緒和連線，進而提高傳輸量。

您可以結合批次處理與水平擴展來提供傳輸量，所需的執行緒、連線和請求的數目會比單獨的訊息請求所需的量更少。您可以使用批次的 Amazon SQS 動作一次傳送、接收、刪除多達 10 則訊息。由於 Amazon SQS 收費是以請求數為準，批次處理可大幅降低您的成本。

批次處理可能會給您的應用程式帶來一些複雜性 (例如，您的應用程式必須將訊息累積起來後再傳送出去，或者有時候必須花更久的時間等待回應)。但是，批次處理在以下情況仍然頗具效益：
+ 應用程式會在短時間內產生許多訊息，所以絕不會延遲太久。
+ 訊息消費者自行從佇列擷取訊息，有別於典型的訊息生產者需要傳送訊息來回應其無法控制的事件。

**重要**  
即使批次中的個別訊息失敗，批次請求也可能會成功。提出批次請求之後，務必確認個別訊息是否出現失敗情況，必要時重試動作。

## 單次操作和批次請求實際可行的 Java 範例
<a name="working-java-example-batch-requests"></a>

### 先決條件
<a name="batch-request-java-example-prerequisites"></a>

新增 `aws-java-sdk-sqs.jar`、`aws-java-sdk-ec2.jar`，以及 `commons-logging.jar` 套件到您的 Java 建置類別路徑。以下範例顯示 Maven 專案 `pom.xml` 檔案中的此等依存關係。

```
<dependencies>
    <dependency>
        <groupId>com.amazonaws</groupId>
        <artifactId>aws-java-sdk-sqs</artifactId>
        <version>{{LATEST}}</version>
    </dependency>
    <dependency>
        <groupId>com.amazonaws</groupId>
        <artifactId>aws-java-sdk-ec2</artifactId>
        <version>{{LATEST}}</version>
    </dependency>
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>{{LATEST}}</version>
    </dependency>
</dependencies>
```

### SimpleProducerConsumer.java
<a name="batch-request-java-example-code"></a>

以下 Java 程式碼範例實作單純的生產者-消費者模式。主要的執行緒會產生數個生產者和消費者執行緒，負責在指定時間處理 1 KB 的訊息。此範例包括提出單次操作請求的生產者和消費者，以及提出批次請求的生產者和消費者。

```
/*
 * Copyright 2010-2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  https://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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.
 *
 */

import com.amazonaws.AmazonClientException;
import com.amazonaws.ClientConfiguration;
import com.amazonaws.services.sqs.AmazonSQS;
import com.amazonaws.services.sqs.AmazonSQSClientBuilder;
import com.amazonaws.services.sqs.model.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Start a specified number of producer and consumer threads, and produce-consume
 * for the least of the specified duration and 1 hour. Some messages can be left
 * in the queue because producers and consumers might not be in exact balance.
 */
public class SimpleProducerConsumer {

    // The maximum runtime of the program.
    private final static int MAX_RUNTIME_MINUTES = 60;
    private final static Log log = LogFactory.getLog(SimpleProducerConsumer.class);

    public static void main(String[] args) throws InterruptedException {

        final Scanner input = new Scanner(System.in);

        System.out.print("Enter the queue name: ");
        final String queueName = input.nextLine();

        System.out.print("Enter the number of producers: ");
        final int producerCount = input.nextInt();

        System.out.print("Enter the number of consumers: ");
        final int consumerCount = input.nextInt();

        System.out.print("Enter the number of messages per batch: ");
        final int batchSize = input.nextInt();

        System.out.print("Enter the message size in bytes: ");
        final int messageSizeByte = input.nextInt();

        System.out.print("Enter the run time in minutes: ");
        final int runTimeMinutes = input.nextInt();

        /*
         * Create a new instance of the builder with all defaults (credentials
         * and region) set automatically. For more information, see Creating
         * Service Clients in the AWS SDK for Java Developer Guide.
         */
        final ClientConfiguration clientConfiguration = new ClientConfiguration()
                .withMaxConnections(producerCount + consumerCount);

        final AmazonSQS sqsClient = AmazonSQSClientBuilder.standard()
                .withClientConfiguration(clientConfiguration)
                .build();

        final String queueUrl = sqsClient
                .getQueueUrl(new GetQueueUrlRequest(queueName)).getQueueUrl();

        // The flag used to stop producer, consumer, and monitor threads.
        final AtomicBoolean stop = new AtomicBoolean(false);

        // Start the producers.
        final AtomicInteger producedCount = new AtomicInteger();
        final Thread[] producers = new Thread[producerCount];
        for (int i = 0; i < producerCount; i++) {
            if (batchSize == 1) {
                producers[i] = new Producer(sqsClient, queueUrl, messageSizeByte,
                        producedCount, stop);
            } else {
                producers[i] = new BatchProducer(sqsClient, queueUrl, batchSize,
                        messageSizeByte, producedCount,
                        stop);
            }
            producers[i].start();
        }

        // Start the consumers.
        final AtomicInteger consumedCount = new AtomicInteger();
        final Thread[] consumers = new Thread[consumerCount];
        for (int i = 0; i < consumerCount; i++) {
            if (batchSize == 1) {
                consumers[i] = new Consumer(sqsClient, queueUrl, consumedCount,
                        stop);
            } else {
                consumers[i] = new BatchConsumer(sqsClient, queueUrl, batchSize,
                        consumedCount, stop);
            }
            consumers[i].start();
        }

        // Start the monitor thread.
        final Thread monitor = new Monitor(producedCount, consumedCount, stop);
        monitor.start();

        // Wait for the specified amount of time then stop.
        Thread.sleep(TimeUnit.MINUTES.toMillis(Math.min(runTimeMinutes,
                MAX_RUNTIME_MINUTES)));
        stop.set(true);

        // Join all threads.
        for (int i = 0; i < producerCount; i++) {
            producers[i].join();
        }

        for (int i = 0; i < consumerCount; i++) {
            consumers[i].join();
        }

        monitor.interrupt();
        monitor.join();
    }

    private static String makeRandomString(int sizeByte) {
        final byte[] bs = new byte[(int) Math.ceil(sizeByte * 5 / 8)];
        new Random().nextBytes(bs);
        bs[0] = (byte) ((bs[0] | 64) & 127);
        return new BigInteger(bs).toString(32);
    }

    /**
     * The producer thread uses {@code SendMessage}
     * to send messages until it is stopped.
     */
    private static class Producer extends Thread {
        final AmazonSQS sqsClient;
        final String queueUrl;
        final AtomicInteger producedCount;
        final AtomicBoolean stop;
        final String theMessage;

        Producer(AmazonSQS sqsQueueBuffer, String queueUrl, int messageSizeByte,
                 AtomicInteger producedCount, AtomicBoolean stop) {
            this.sqsClient = sqsQueueBuffer;
            this.queueUrl = queueUrl;
            this.producedCount = producedCount;
            this.stop = stop;
            this.theMessage = makeRandomString(messageSizeByte);
        }

        /*
         * The producedCount object tracks the number of messages produced by
         * all producer threads. If there is an error, the program exits the
         * run() method.
         */
        public void run() {
            try {
                while (!stop.get()) {
                    sqsClient.sendMessage(new SendMessageRequest(queueUrl,
                            theMessage));
                    producedCount.incrementAndGet();
                }
            } catch (AmazonClientException e) {
                /*
                 * By default, AmazonSQSClient retries calls 3 times before
                 * failing. If this unlikely condition occurs, stop.
                 */
                log.error("Producer: " + e.getMessage());
                System.exit(1);
            }
        }
    }

    /**
     * The producer thread uses {@code SendMessageBatch}
     * to send messages until it is stopped.
     */
    private static class BatchProducer extends Thread {
        final AmazonSQS sqsClient;
        final String queueUrl;
        final int batchSize;
        final AtomicInteger producedCount;
        final AtomicBoolean stop;
        final String theMessage;

        BatchProducer(AmazonSQS sqsQueueBuffer, String queueUrl, int batchSize,
                      int messageSizeByte, AtomicInteger producedCount,
                      AtomicBoolean stop) {
            this.sqsClient = sqsQueueBuffer;
            this.queueUrl = queueUrl;
            this.batchSize = batchSize;
            this.producedCount = producedCount;
            this.stop = stop;
            this.theMessage = makeRandomString(messageSizeByte);
        }

        public void run() {
            try {
                while (!stop.get()) {
                    final SendMessageBatchRequest batchRequest =
                            new SendMessageBatchRequest().withQueueUrl(queueUrl);

                    final List<SendMessageBatchRequestEntry> entries =
                            new ArrayList<SendMessageBatchRequestEntry>();
                    for (int i = 0; i < batchSize; i++)
                        entries.add(new SendMessageBatchRequestEntry()
                                .withId(Integer.toString(i))
                                .withMessageBody(theMessage));
                    batchRequest.setEntries(entries);

                    final SendMessageBatchResult batchResult =
                            sqsClient.sendMessageBatch(batchRequest);
                    producedCount.addAndGet(batchResult.getSuccessful().size());

                    /*
                     * Because SendMessageBatch can return successfully, but
                     * individual batch items fail, retry the failed batch items.
                     */
                    if (!batchResult.getFailed().isEmpty()) {
                        log.warn("Producer: retrying sending "
                                + batchResult.getFailed().size() + " messages");
                        for (int i = 0, n = batchResult.getFailed().size();
                             i < n; i++) {
                            sqsClient.sendMessage(new
                                    SendMessageRequest(queueUrl, theMessage));
                            producedCount.incrementAndGet();
                        }
                    }
                }
            } catch (AmazonClientException e) {
                /*
                 * By default, AmazonSQSClient retries calls 3 times before
                 * failing. If this unlikely condition occurs, stop.
                 */
                log.error("BatchProducer: " + e.getMessage());
                System.exit(1);
            }
        }
    }

    /**
     * The consumer thread uses {@code ReceiveMessage} and {@code DeleteMessage}
     * to consume messages until it is stopped.
     */
    private static class Consumer extends Thread {
        final AmazonSQS sqsClient;
        final String queueUrl;
        final AtomicInteger consumedCount;
        final AtomicBoolean stop;

        Consumer(AmazonSQS sqsClient, String queueUrl, AtomicInteger consumedCount,
                 AtomicBoolean stop) {
            this.sqsClient = sqsClient;
            this.queueUrl = queueUrl;
            this.consumedCount = consumedCount;
            this.stop = stop;
        }

        /*
         * Each consumer thread receives and deletes messages until the main
         * thread stops the consumer thread. The consumedCount object tracks the
         * number of messages that are consumed by all consumer threads, and the
         * count is logged periodically.
         */
        public void run() {
            try {
                while (!stop.get()) {
                    try {
                        final ReceiveMessageResult result = sqsClient
                                .receiveMessage(new
                                        ReceiveMessageRequest(queueUrl));

                        if (!result.getMessages().isEmpty()) {
                            final Message m = result.getMessages().get(0);
                            sqsClient.deleteMessage(new
                                    DeleteMessageRequest(queueUrl,
                                    m.getReceiptHandle()));
                            consumedCount.incrementAndGet();
                        }
                    } catch (AmazonClientException e) {
                        log.error(e.getMessage());
                    }
                }
            } catch (AmazonClientException e) {
                /*
                 * By default, AmazonSQSClient retries calls 3 times before
                 * failing. If this unlikely condition occurs, stop.
                 */
                log.error("Consumer: " + e.getMessage());
                System.exit(1);
            }
        }
    }

    /**
     * The consumer thread uses {@code ReceiveMessage} and {@code
     * DeleteMessageBatch} to consume messages until it is stopped.
     */
    private static class BatchConsumer extends Thread {
        final AmazonSQS sqsClient;
        final String queueUrl;
        final int batchSize;
        final AtomicInteger consumedCount;
        final AtomicBoolean stop;

        BatchConsumer(AmazonSQS sqsClient, String queueUrl, int batchSize,
                      AtomicInteger consumedCount, AtomicBoolean stop) {
            this.sqsClient = sqsClient;
            this.queueUrl = queueUrl;
            this.batchSize = batchSize;
            this.consumedCount = consumedCount;
            this.stop = stop;
        }

        public void run() {
            try {
                while (!stop.get()) {
                    final ReceiveMessageResult result = sqsClient
                            .receiveMessage(new ReceiveMessageRequest(queueUrl)
                                    .withMaxNumberOfMessages(batchSize));

                    if (!result.getMessages().isEmpty()) {
                        final List<Message> messages = result.getMessages();
                        final DeleteMessageBatchRequest batchRequest =
                                new DeleteMessageBatchRequest()
                                        .withQueueUrl(queueUrl);

                        final List<DeleteMessageBatchRequestEntry> entries =
                                new ArrayList<DeleteMessageBatchRequestEntry>();
                        for (int i = 0, n = messages.size(); i < n; i++)
                            entries.add(new DeleteMessageBatchRequestEntry()
                                    .withId(Integer.toString(i))
                                    .withReceiptHandle(messages.get(i)
                                            .getReceiptHandle()));
                        batchRequest.setEntries(entries);

                        final DeleteMessageBatchResult batchResult = sqsClient
                                .deleteMessageBatch(batchRequest);
                        consumedCount.addAndGet(batchResult.getSuccessful().size());

                        /*
                         * Because DeleteMessageBatch can return successfully,
                         * but individual batch items fail, retry the failed
                         * batch items.
                         */
                        if (!batchResult.getFailed().isEmpty()) {
                            final int n = batchResult.getFailed().size();
                            log.warn("Producer: retrying deleting " + n
                                    + " messages");
                            for (BatchResultErrorEntry e : batchResult
                                    .getFailed()) {

                                sqsClient.deleteMessage(
                                        new DeleteMessageRequest(queueUrl,
                                                messages.get(Integer
                                                        .parseInt(e.getId()))
                                                        .getReceiptHandle()));

                                consumedCount.incrementAndGet();
                            }
                        }
                    }
                }
            } catch (AmazonClientException e) {
                /*
                 * By default, AmazonSQSClient retries calls 3 times before
                 * failing. If this unlikely condition occurs, stop.
                 */
                log.error("BatchConsumer: " + e.getMessage());
                System.exit(1);
            }
        }
    }

    /**
     * This thread prints every second the number of messages produced and
     * consumed so far.
     */
    private static class Monitor extends Thread {
        private final AtomicInteger producedCount;
        private final AtomicInteger consumedCount;
        private final AtomicBoolean stop;

        Monitor(AtomicInteger producedCount, AtomicInteger consumedCount,
                AtomicBoolean stop) {
            this.producedCount = producedCount;
            this.consumedCount = consumedCount;
            this.stop = stop;
        }

        public void run() {
            try {
                while (!stop.get()) {
                    Thread.sleep(1000);
                    log.info("produced messages = " + producedCount.get()
                            + ", consumed messages = " + consumedCount.get());
                }
            } catch (InterruptedException e) {
                // Allow the thread to exit.
            }
        }
    }
}
```

### 監控範本執行階段的數量指標
<a name="batch-request-java-example-monitoring-metrics"></a>

Amazon SQS 會自動為傳送、接收及刪除的訊息產生數量指標。您可以透過佇列的**監控**索引標籤或 [CloudWatch 主控台](https://console.aws.amazon.com/cloudwatch/home)存取這類指標和其他項目。

**注意**  
可能要在佇列開始執行達 15 分鐘後方可取得指標。