Pick the first broker that's not down as preferred#34
Pick the first broker that's not down as preferred#34psycotica0-shopify wants to merge 1 commit intowvanbergen:masterfrom
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| def preferred_leader | ||
| @replicas.first | ||
| @replicas.compact.first |
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I think the problem lies somewhere else.
Kafka stores the replicas in order of preference. The first one is the preferred replica. E.g. [1,2,3], in which 1 is the preferred one.
In this case, 1 doesn't get set because that broker is down. However, that doesn't change the fact that 1 is the preferred replica. The real issue is: why does it show up as nil when it is down?
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Sorry, I was AFK for a week.
replicas is passed into the constructor for partition in topic.
Around line 171 it gets the list of replica ids from each partition of the topic, and indexes into cluster.brokers[id] to try and turn the id into a broker.
If the cluster doesn't contain that broker object, then that returns nil.
Should it be filtered out at that level, and only up brokers be in the replicas array, or should the cluster know about the down broker, even if it's down?
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My preference would be that we still have a Broker object with the proper ID, but with an (un)available? method. That way we can do things like partition.preferred_replica.available?
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If a broker was down, but a partition had it at the head of its replica list, preferred_leader was
nil, even when other replicas were up.