[KUDU-298] Evaluate replica Apply() perf vs the leader and make replica Apply()s multi-threaded if it makes sense

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Not A Bug
• Affects Version/s: M3
• Component/s: perf
• Target Version/s: Public beta
• Assignee: Unassigned
• Reporter: David Alves
• Created: 27/May/14 17:18
• Updated: 20/Aug/15 21:48
• Resolved: 20/Aug/15 21:48

Description

Replicas, similarly to the leader, can semantically run Apply() concurrently. However this brings a reasonable amount of havoc as different replicas will have commits in different orders which needs to be dealt with in multiple places.

We should measure if the leader is ever slowing down for replicas and if so bite the bullet and make the replica apply()s multithreaded.