[KUDU-288] TRACE in scan path costs a lot of CPU

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: M4
• Component/s: perf, tserver
• Target Version/s: M4
• Code Review: http://gerrit.ent.cloudera.com:8080/2786
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 21/May/14 13:30
• Updated: 09/Jun/14 16:45
• Resolved: 09/Jun/14 16:45

Description

In a profile of a big scan, I see the TRACE call in the inner loop of HandleContinueScanRequest is costing a lot of CPU. This is likely because my particular scan is hitting MRS a lot, so each batch is only a few rows. But we should probably remove this trace or otherwise rate-limit it.