[ZOOKEEPER-578] ResponderThread should be able to use TCP or UDP

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 3.2.1
• Component/s: server
• Assignee: Henry Robinson
• Reporter: Henry Robinson
• Created: 11/Nov/09 18:37
• Updated: 03/Apr/12 21:16
• Resolved: 03/Apr/12 21:16

Description

The ResponderThread, which responds to inquiries for the current leader, currently only uses UDP. It also only runs for electionAlg=0.

Observers will eventually require that a ResponderThread runs for all election types. However, this introduces a UDP dependency which some installations do not want. This would also allow such installations to use electionAlg=0 (although this is not a big win as it is the least sophisticated election algorithm).

Therefore we should be able to toggle ResponderThread to use either TCP or UDP. Since UDP is more performant, it probably makes sense to retain it. So I propose to choose between the two at startup time using a configuration flag responderTCP=true.

Fixing this issue exposed ZOOKEEPER-569, on which this JIRA depends.