NodeJS：处理突然的云 Pub/Sub 删除

Posted 2023-02-16

【中文标题】NodeJS：处理突然的云 Pub/Sub 删除

【英文标题】：NodeJS: handling sudden cloud Pub/Sub deletion

【发布时间】：2021-05-08 03:13:11

【问题描述】：

我正在开发一个侦听 Google Cloud Pub/Sub 订阅的 NodeJS 应用程序。 这是我的相关代码：

const messageHandler = message => 
    console.log(message.id);
;
subscription.on("message", messageHandler);

作为系统架构的一部分，订阅可能会被外部资源突然删除，在这种情况下，我的应用程序会因以下错误日志而崩溃：

events.js:174
  throw er; // Unhandled 'error' event
  ^

Error: Resource not found (resource=projects/proj-name/subscriptions/subscription-name).
    at MessageStream._onEnd (/Users/admin/Projects/proj-name/socket_server/node_modules/@google-cloud/pubsub/build/src/message-stream.js:244:26)
    at MessageStream._onStatus (/Users/admin/Projects/proj-name/node_modules/@google-cloud/pubsub/build/src/message-stream.js:281:18)
    at ClientDuplexStreamImpl.stream.on.once.status (/Users/admin/Projects/proj-name/node_modules/@google-cloud/pubsub/build/src/message-stream.js:146:44)
    at Object.onceWrapper (events.js:286:20)
    at ClientDuplexStreamImpl.emit (events.js:198:13)
    at Object.onReceiveStatus (/Users/admin/Projects/proj-name/node_modules/@grpc/grpc-js/build/src/client.js:389:24)
    at Object.onReceiveStatus (/Users/admin/Projects/proj-name/node_modules/@grpc/grpc-js/build/src/client-interceptors.js:299:181)
    at process.nextTick (/Users/admin/Projects/proj-name/node_modules/@grpc/grpc-js/build/src/call-stream.js:130:78)
    at process._tickCallback (internal/process/next_tick.js:61:11)
Emitted 'error' event at:
    at Subscriber.Subscription._subscriber.on.err (/Users/admin/Projects/proj-name/node_modules/@google-cloud/pubsub/build/src/subscription.js:198:38)
    at Subscriber.emit (events.js:198:13)
    at MessageStream._stream.on.err (/Users/admin/Projects/proj-name/node_modules/@google-cloud/pubsub/build/src/subscriber.js:328:38)
    at MessageStream.emit (events.js:198:13)
    at emitErrorNT (internal/streams/destroy.js:91:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:59:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)

有没有办法优雅地处理这种删除？ 谢谢

【参考方案1】：

您可以查看 nodejs error handling for subscribers 的 pub/sub 文档。

脚本的实现会持续监听错误或消息，直到达到分配的超时时间。

顺便说一句，您应该设置一个新订阅者并重置监听或重新创建已删除的订阅者并监听该主题。

这是pub/sub subscriber error handling中的代码sn-p：

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const subscriptionName = 'YOUR_SUBSCRIPTION_NAME';
// const timeout = 10;

// Imports the Google Cloud client library
const PubSub = require('@google-cloud/pubsub');

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

function listenForErrors() 
  // References an existing subscription
  const subscription = pubSubClient.subscription(subscriptionName);

  // Create an event handler to handle messages
  const messageHandler = function (message) 
    // Do something with the message
    console.log(`Message: $message`);

    // "Ack" (acknowledge receipt of) the message
    message.ack();
  ;

  // Create an event handler to handle errors
  const errorHandler = function (error) 
    // Do something with the error
    console.error(`ERROR: $error`);
    throw error;
  ;

  // Listen for new messages/errors until timeout is hit
  subscription.on('message', messageHandler);
  subscription.on('error', errorHandler);

  setTimeout(() => 
    subscription.removeListener('message', messageHandler);
    subscription.removeListener('error', errorHandler);
  , timeout * 1000);


listenForErrors();

这是我做的一个测试：