[Bug] The TopicName cache will not shrink if a topic is created and deleted

[BewareMyPower]

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• I searched in the issues and found nothing similar.

Read release policy

• I understand that unsupported versions don't get bug fixes. I will attempt to reproduce the issue on a supported version of Pulsar client and Pulsar broker.

User environment

4.0.5

Issue Description

See #24458 (review)

Error messages

N/A

Reproducing the issue

Run the standalone.

Run the following application a few times:

        final var admin = PulsarAdmin.builder().serviceHttpUrl("http://localhost:8080").build();
        final var random = new Random();
        for (int i = 0; i < 100000; i++) {
            final var topic = "new-test-" + random.nextInt(10000000);
            admin.topics().createNonPartitionedTopic(topic);
            admin.topics().delete(topic);
        }

Even though there is no traffic, the TopicName's cache kept growing.

There were only 3 active topics but 20.3k TopicName cache entries.

Additional information

It's caused by the design of #23052, which has no limits to the TopicName's cache. It relies on the scheduled task to clear the whole cache if the size has reached 200000, the task is scheduled every 2 hours.

P.S. The proxy side didn't schedule the task before, so it caused an OOM here #24445

From the benchmark shown here, the performance of the cache will be downgraded if there are many keys.

Are you willing to submit a PR?

• I'm willing to submit a PR!

[BewareMyPower]

@lhotari Could you run a similar test based on the new cache design here? #24457 I believe it could be a better cache solution since the soft references could be garbage collected.