rkaw92 opened a new issue #152:
URL: https://github.com/apache/pulsar-client-node/issues/152
Hi,
I have a use case where I expose a Pulsar topic over HTTP via Server-Sent
Events. Basically, when a client connects over HTTP, I do this:
```js
const reader = await client.createReader({
topic: request.params.topic,
startMessageId: request.headers['last-event-id'] ?
Pulsar.MessageId.deserialize(Buffer.from(request.headers['last-event-id'],
'base64')) :
Pulsar.MessageId.earliest()
});
```
Then I use a loop that reads messages as they come and sends them to the
client:
```js
while (!clientGoneAway) {
let message;
message = await reader.readNext();
reply.raw.write(formatServerSentEvent(
message.getMessageId().serialize().toString('base64'),
message.getData().toString('utf-8')
));
}
```
Additionally, the server detects the `close` event on the HTTP requests,
closes the reader and prevents further iteration:
```js
request.raw.once('close', async function() {
clientGoneAway = true;
await reader.close();
reply.raw.end();
})
```
(`request.raw` and `reply.raw` are Node.js req and res objects, respectively
- they're just wrapped like this in Fastify.js)
Now, my problem is that even if I call `reader.close()`, the
`reader.readNext();` never resolves nor rejects. It's not just a Promise
problem - it seems like it's keeping a thread busy, because then all other
operations hang: things like `fs.createReadStream`, as well as creating new
readers, hang forever until I completely restart the Node.js process.
I know I can use a timeout with `reader.readNext(timeoutMS)`, but this has 2
major disadvantages:
* It turns the reader into a kind of poller
* It still does not vacate the thread - so it's possible to trivially
saturate the thread pool by creating more readers than the pool size within the
timeout period (so for example 4 readers in 1 second, when using a timeout of
1000 ms)
Is there any way to have the reader immediately abort all reads when closed?
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