[IMPALA-3972] Improve /varz by using structured gflags API

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Impala 2.7.0
• Fix Version/s: Impala 2.7.0
• Component/s: Backend
• Labels: observability ramp-up supportability
• Assignee: Henry Robinson
• Reporter: Henry Robinson
• Created: 11/Aug/16 04:29
• Updated: 15/Aug/16 05:39
• Resolved: 15/Aug/16 05:39

Description

/varz is generated by dumping a text string of all flags to a webpage. But there are APIs in gflags that allow us to do better, by getting a struct for each flag that gives its name, default value etc. This can allow us to more quickly tell if a flag has changed from its default value, which is a supportability gain.