Producers or consumers may be closed after the client exits out of scope

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript, node.js
Domain
backend, distributed-systems

Research direction

No source files or tests are named. Start by running the reproduction against a local Pulsar broker, then trace producer, consumer, and client lifetime handling in the Node.js client; done means a producer or consumer keeps its client usable after the outer function scope ends and a regression test prevents AlreadyClosed during continued sends.

Written by the indexing model from the issue text.

Description

Here is the reproduction code:

const Pulsar = require('pulsar-client');

(async () => {
  // Create a client
  const client = new Pulsar.Client({
    serviceUrl: 'pulsar://localhost:6650'
  });

  // Create a producer
  const producer = await client.createProducer({
    topic: 'persistent://public/default/my-topic',
  });
  
  const sendRecords = async () => {
    // Send a message
    await producer.send({
        data: Buffer.from("hello")
    });

    console.log("sent hello")
    setTimeout(()=>sendRecords(), 1000)
  }

  
  await sendRecords();
})();

The output would be like:

➜  node node index.js
sent hello
sent hello
sent hello
sent hello
sent hello
sent hello
sent hello
node:internal/process/promises:288
            triggerUncaughtException(err, true /* fromPromise */);
            ^

[Error: Failed to send message: AlreadyClosed]

Node.js v18.19.0

After the client exits the outer function's scope, it will eventually be garbage collected. This closes the producers and causes the AlreadyClosed issue.

A workaround is to pass the client ref to the sendRecords function:

  const sendRecords = async (client) => {
    // Send a message
    await producer.send({
        data: Buffer.from("hello")
    });

    console.log("sent hello")
    setTimeout(()=>sendRecords(client), 1000)
  }

  
  await sendRecords(client);

And it works.

A better approach is to keep a reference to the client inside the producer or consumer. This way, as long as we hold a reference to the producer or consumer, the client object will not be garbage collected.

Dominant language
C++
Stars
164
Forks
99
Avg merge
5d 18h
Merged PRs (30d)
2

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