[RATIS-967] Support priority in leader election

• Type: Task
• Status: Resolved
• Priority: Major
• Resolution: Resolved
• Affects Version/s: 0.5.0
• Fix Version/s: 2.0.0
• Component/s: raft-group
• Assignee: runzhiwang
• Reporter: Baolong Mao
• Created: 04/Jun/20 06:20
• Updated: 06/Nov/23 06:21
• Resolved: 31/Aug/20 07:56

Description

In some applications, some servers in a raft group are more preferable to be the leader than the other servers. For example, a server is colocated with other resources so that having the server as the leader is more efficient than the other servers.

In this JIRA, we propose adding priority to each server so that the higher priority server(s) will always win the leader election when they are available.

Issue Links

• duplicates: RATIS-800 Make Ratis consume recommended leader host from the pipeline creator
• is related to: RATIS-995 Leader balance in multi raft
• links to: GitHub Pull Request #175

Sub-Tasks

• Change RaftPeer and proto to support priority: Resolved
• Change leader election to add priority consideration: Resolved
• Change leader heartbeat to yield to a higher priority leader.: Resolved
• Change client to try the servers according to the priority.: Resolved
• Fix can not elect leader when higher priority server crash: Resolved
• Support change priority dynamically: Resolved
• Fix leader election with priority too slow: Open