[KUDU-997] Expose client-side metrics

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Feature Complete
• Component/s: client
• Labels: roadmap-candidate
• Assignee: Unassigned
• Reporter: Adar Dembo
• Created: 14/Aug/15 13:12
• Updated: 18/Jun/19 13:02

Description

I think client-side metrics have been a desirable feature for quite some time, but I especially wanted them while debugging KUDU-993.

There are some challenges in collecting metric data in a cohesive way across the client (at least in C++, where there isn't a completely uniform way to send/receive RPCs). But I think the main challenge is figuring out how to expose it to users. I'm not sure we want to expose metrics.h directly, because it's deeply intertwined with gutil and other Kudu util code.

I'm attaching a patch I wrote yesterday to help with KUDU-993. It doesn't tackle the API problem at all, but shows how to build a histogram tracking all writes.