[HDFS-13702] Remove HTrace hooks from DFSClient to reduce CPU usage

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 3.2.0, 3.1.1, 3.0.4
• Component/s: performance
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 26/Jun/18 17:48
• Updated: 02/Jul/18 10:49
• Resolved: 02/Jul/18 10:12

Description

I am seeing DFSClient.newReaderTraceScope take ~15% CPU in a teravalidate workload even when HTrace is disabled. This is because it stringifies several integers. We should avoid all allocation and stringification when htrace is disabled.

Issue Links

• relates to: HADOOP-15566 Support OpenTelemetry