Producer hangs when using BatchBuilder.KeyBased

When using the KEY_BASED BatchBuilder it is impossible to send messages. The producer hangs forever and nothing happens.

Sample code:

var client = await new PulsarClientBuilder()
    .ServiceUrl("pulsar://localhost:6650")
    .BuildAsync();

await using var producer = await client.NewProducer(Schema.STRING())
    .Topic("some-topic")
    .EnableBatching(true)
    .BatchBuilder(BatchBuilder.KeyBased)
    .CreateAsync();

// this hangs when using BatchBuilder.KeyBased
await producer.SendAsync("Oh no!");

I’ve tested this code against pulsar:2.11.0 and pulsar:3.0.0. The Pulsar.Client version is 2.12.6.

[Lanayx]

I’ve pushed a fix for empty key case, will publish a nuget once CI will pass. However what I’ve found that the docs from pulsar site you linked don’t correspond to the code - NON_KEY value is never sent (such thing doesn’t exist in the codebase) so I just used empty string as well.

[adrianotr]

To answer my own question:

What should happen when messages have an OrderingKey?

It will use the ordering key as the batch key, when the ordering key is specified, as seen in the source code.