[HDFS-8088] Reduce the number of HTrace spans generated by HDFS reads

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Assignee: Colin McCabe
• Reporter: Colin McCabe
• Created: 08/Apr/15 02:11
• Updated: 18/Jun/19 05:25
• Resolved: 18/Jun/19 05:25

Description

HDFS generates too many trace spans on read right now. Every call to read() we make generates its own span, which is not very practical for things like HBase or Accumulo that do many such reads as part of a single operation. Instead of tracing every call to read(), we should only trace the cases where we refill the buffer inside a BlockReader.

Issue Links

• relates to: HDFS-8069 Tracing implementation on DFSInputStream seriously degrades performance