代码之家 › 专栏 › 技术社区 › Forepick

NodeJS:处理云Pub/Sub的突然删除

google-cloud-pubsub google-cloud-platform node.js

Forepick · 技术社区 · 4 年前

我正在开发一个NodeJS应用程序,它可以监听Google Cloud Pub/Sub订阅。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,订阅可能会突然被外部资源删除,在这种情况下,我的应用程序刚刚崩溃,并显示以下错误日志:

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)

有什么方法可以优雅地处理这种删除吗? 谢谢

0 回复 | 直到 4 年前

Ricco D 4 年前

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

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,您应该设置一个新的订阅者并重置监听,或者重新创建已删除的订阅者并监听该主题。

以下是 pub/sub subscriber error handling :

/**
 * 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: