Re: [DISCUSSION] PIP-122: Change loadBalancer default loadSheddingStrategy to ThresholdShedder

[Michael Marshall]

Hi Hang Chen,

I support changing the default for 2.10.

However, as far as I can tell, there are unit tests for the
`OverloadShedder` class but not for the `ThresholdShedder` class. I
think we should add unit tests before we change the default.

Regarding integration tests, I assume that we implicitly test the
default LoadShedder, but I haven't checked myself.

Thanks,
Michael

On Tue, Jan 4, 2022 at 8:24 AM Hang Chen <chenh...@apache.org> wrote:
>
> https://github.com/apache/pulsar/issues/13340
>
> Pasted below for quoting convenience.
>
> ----
> ### Motivation
> The ThresholdShedder load balance policy since Pulsar 2.6.0 by
> https://github.com/apache/pulsar/pull/6772. It can resolve many load
> balance issues of `OverloadShedder` and works well in many Pulsar
> production clusters.
>
> In Pulsar 2.6.0, 2.7.0, 2.8.0 and 2.9.0, Pulsar's default load balance
> policy is `OverloadShedder`.
>
> I think it's a good time for 2.10 to change default load balance
> policy to `ThresholdShedder`, it will make throughput more balance
> between brokers.
>
> ### Proposed Changes
> In 2.10 release，for `broker.conf`, change
> `loadBalancerLoadSheddingStrategy` from
> `org.apache.pulsar.broker.loadbalance.impl.OverloadShedder` to
> `org.apache.pulsar.broker.loadbalance.impl.ThresholdShedder`