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

[RobertIndie]

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.