透過並行控制程序發布

設定發布者，讓發布訊息和處理訊息 Future 時使用不同數量的執行緒。

深入探索

如需包含這個程式碼範例的詳細說明文件，請參閱下列內容：

程式碼範例

C++

在試用這個範例之前，請先按照C++「Pub/Sub 快速入門導覽課程：使用用戶端程式庫」中的操作說明進行設定。 詳情請參閱 Pub/Sub C++ API 參考說明文件。

如要驗證 Pub/Sub，請設定應用程式預設憑證。 詳情請參閱「為本機開發環境設定驗證」。

namespace pubsub = ::google::cloud::pubsub;
using ::google::cloud::future;
using ::google::cloud::GrpcBackgroundThreadPoolSizeOption;
using ::google::cloud::Options;
using ::google::cloud::StatusOr;
[](std::string project_id, std::string topic_id) {
  auto topic = pubsub::Topic(std::move(project_id), std::move(topic_id));
  // Override the default number of background (I/O) threads. By default the
  // library uses `std::thread::hardware_concurrency()` threads.
  auto options = Options{}.set<GrpcBackgroundThreadPoolSizeOption>(8);
  auto publisher = pubsub::Publisher(
      pubsub::MakePublisherConnection(std::move(topic), std::move(options)));

  std::vector<future<void>> ids;
  for (char const* data : {"1", "2", "3", "go!"}) {
    ids.push_back(
        publisher.Publish(pubsub::MessageBuilder().SetData(data).Build())
            .then([data](future<StatusOr<std::string>> f) {
              auto s = f.get();
              if (!s) return;
              std::cout << "Sent '" << data << "' (" << *s << ")\n";
            }));
  }
  publisher.Flush();
  // Block until they are actually sent.
  for (auto& id : ids) id.get();
}

Go

在試用這個範例之前，請先按照Go「Pub/Sub 快速入門導覽課程：使用用戶端程式庫」中的操作說明進行設定。 詳情請參閱 Pub/Sub Go API 參考說明文件。

如要驗證 Pub/Sub，請設定應用程式預設憑證。 詳情請參閱「為本機開發環境設定驗證」。

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub/v2"
)

func publishSingleGoroutine(w io.Writer, projectID, topicID, msg string) error {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	// msg := "Hello World"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	// client.Publisher can be passed a topic ID (e.g. "my-topic") or
	// a fully qualified name (e.g. "projects/my-project/topics/my-topic").
	// If a topic ID is provided, the project ID from the client is used.
	publisher := client.Publisher(topicID)
	publisher.PublishSettings.NumGoroutines = 1

	result := publisher.Publish(ctx, &pubsub.Message{Data: []byte(msg)})
	// Block until the result is returned and a server-generated
	// ID is returned for the published message.
	id, err := result.Get(ctx)
	if err != nil {
		return fmt.Errorf("Get: %w", err)
	}
	fmt.Fprintf(w, "Published a message; msg ID: %v\n", id)
	return nil
}

Java

在試用這個範例之前，請先按照Java「Pub/Sub 快速入門導覽課程：使用用戶端程式庫」中的操作說明進行設定。 詳情請參閱 Pub/Sub Java API 參考說明文件。

如要驗證 Pub/Sub，請設定應用程式預設憑證。 詳情請參閱「為本機開發環境設定驗證」。


import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutures;
import com.google.api.gax.core.ExecutorProvider;
import com.google.api.gax.core.InstantiatingExecutorProvider;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

public class PublishWithConcurrencyControlExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String topicId = "your-topic-id";

    publishWithConcurrencyControlExample(projectId, topicId);
  }

  public static void publishWithConcurrencyControlExample(String projectId, String topicId)
      throws IOException, ExecutionException, InterruptedException {
    TopicName topicName = TopicName.of(projectId, topicId);
    Publisher publisher = null;
    List<ApiFuture<String>> messageIdFutures = new ArrayList<>();

    try {
      // Provides an executor service for processing messages. The default
      // `executorProvider` used by the publisher has a default thread count of
      // 5 * the number of processors available to the Java virtual machine.
      ExecutorProvider executorProvider =
          InstantiatingExecutorProvider.newBuilder().setExecutorThreadCount(4).build();

      // `setExecutorProvider` configures an executor for the publisher.
      publisher = Publisher.newBuilder(topicName).setExecutorProvider(executorProvider).build();

      // schedule publishing one message at a time : messages get automatically batched
      for (int i = 0; i < 100; i++) {
        String message = "message " + i;
        ByteString data = ByteString.copyFromUtf8(message);
        PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();

        // Once published, returns a server-assigned message id (unique within the topic)
        ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage);
        messageIdFutures.add(messageIdFuture);
      }
    } finally {
      // Wait on any pending publish requests.
      List<String> messageIds = ApiFutures.allAsList(messageIdFutures).get();

      System.out.println("Published " + messageIds.size() + " messages with concurrency control.");

      if (publisher != null) {
        // When finished with the publisher, shutdown to free up resources.
        publisher.shutdown();
        publisher.awaitTermination(1, TimeUnit.MINUTES);
      }
    }
  }
}

Ruby

在試用這個範例之前，請先按照Ruby「Pub/Sub 快速入門導覽課程：使用用戶端程式庫」中的操作說明進行設定。 詳情請參閱 Pub/Sub Ruby API 參考說明文件。

如要驗證 Pub/Sub，請設定應用程式預設憑證。 詳情請參閱「為本機開發環境設定驗證」。

# topic_id = "your-topic-id"

pubsub = Google::Cloud::PubSub.new
publisher = pubsub.publisher topic_id, async: {
  threads: {
    # Use exactly one thread for publishing message and exactly one thread
    # for executing callbacks
    publish:  1,
    callback: 1
  }
}

publisher.publish_async "This is a test message." do |result|
  raise "Failed to publish the message." unless result.succeeded?
  puts "Message published asynchronously."
end

# Stop the async_publisher to send all queued messages immediately.
publisher.async_publisher.stop.wait!

後續步驟

如要搜尋及篩選其他 Google Cloud 產品的程式碼範例，請參閱Google Cloud 範例瀏覽器。