通过并发控制进行发布

将发布者配置为为发布消息和处理未来消息使用不同数量的线程。

包含此代码示例的文档页面

如需查看上下文中使用的代码示例,请参阅以下文档:

代码示例

C++

在尝试此示例之前,请按照《Pub/Sub 快速入门:使用客户端库》中的 C++ 设置说明进行操作。如需了解详情,请参阅 Pub/Sub C++ API 参考文档

namespace pubsub = google::cloud::pubsub;
using google::cloud::future;
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 =
      pubsub::ConnectionOptions{}.set_background_thread_pool_size(8);
  auto publisher = pubsub::Publisher(pubsub::MakePublisherConnection(
      std::move(topic), pubsub::PublisherOptions{}, 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

在尝试此示例之前,请按照《Pub/Sub 快速入门:使用客户端库》中的 Go 设置说明执行操作。如需了解详情,请参阅 Pub/Sub Go API 参考文档

import (
	"context"
	"fmt"
	"io"

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

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: %v", err)
	}

	t := client.Topic(topicID)
	t.PublishSettings.NumGoroutines = 1

	result := t.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: %v", err)
	}
	fmt.Fprintf(w, "Published a message; msg ID: %v\n", id)
	return nil
}

Java

在尝试此示例之前,请按照《Pub/Sub 快速入门:使用客户端库》中的 Java 设置说明执行操作。如需了解详情,请参阅 Pub/Sub Java API 参考文档


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

在尝试此示例之前,请按照《Pub/Sub 快速入门:使用客户端库》中的 Ruby 设置说明执行操作。如需了解详情,请参阅 Pub/Sub Ruby API 参考文档

# topic_id = "your-topic-id"
require "google/cloud/pubsub"

pubsub = Google::Cloud::Pubsub.new

topic = pubsub.topic topic_id, async: {
  threads: {
    # Use exactly one thread for publishing message and exactly one thread
    # for executing callbacks
    publish:  1,
    callback: 1
  }
}
topic.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.
topic.async_publisher.stop.wait!

后续步骤

如需搜索和过滤其他 Google Cloud 产品的代码示例,请参阅 Google Cloud 示例浏览器