Add tests for the dispatcherMaxRoundRobinBatchSize config

[BewareMyPower]

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Motivation

This config limits the max number of entries to dispatch for a Shared or Key_Shared subscription. However, there is no related test, so a regression could be introduced.

See

pulsar/pulsar-broker-common/src/main/java/org/apache/pulsar/broker/ServiceConfiguration.java

Line 1299 in 3e6f7de

private int dispatcherMaxRoundRobinBatchSize = 20;

I added a TODO here:

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentDispatcherMultipleConsumers.java

Line 852 in 76e9f9f

// TODO: add tests to verify dispatcherMaxRoundRobinBatchSize is respected

If this line was changed like:

            int maxEntriesInThisBatch =
                            // use the average batch size per message to calculate the number of entries to
                            // dispatch. round up to the next integer without using floating point arithmetic.
                            (maxMessagesInThisBatch + avgBatchSizePerMsg - 1) / avgBatchSizePerMsg);

no tests will fail. This is dangerous because there is no test that guarantees the config works

Solution

No response

Alternatives

No response

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!

[3pacccccc]

i'm interest in this issue, assign to me please.

[jojowyh]

I'm new to an open source project in China, and I would like to participate in this issue as well

[BewareMyPower]

I see @jojowyh already pushed a PR, so I assigned this issue to him for now. I left a requested change here: #24110 (comment) and I also updated this issue description.

@3pacccccc If you're also interested in this issue, welcome to push a PR as well.