[HDFS-10662] Optimize UTF8 string/byte conversions

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.8.0, 2.7.4, 3.0.0-alpha1
• Component/s: hdfs
• Target Version/s: 2.9.0
• Hadoop Flags: Reviewed
• Assignee: Daryn Sharp
• Reporter: Daryn Sharp
• Created: 20/Jul/16 18:14
• Updated: 20/Sep/16 08:33
• Resolved: 01/Sep/16 22:29

Description

String/byte conversions may take either a Charset instance or its canonical name. One might think a Charset instance would be faster due to avoiding a lookup and instantiation of a Charset, but it's not. The canonical string name variants will cache the string encoder/decoder (obtained from a Charset) resulting in better performance.

LOG4J2-935 describes a real-world performance boost. I micro-benched a marginal runtime improvement on jdk 7/8. However for a 16 byte path, using the canonical name generated 50% less garbage. For a 64 byte path, 25% of the garbage. Given the sheer number of times that paths are (re)parsed, the cost adds up quickly.

Issue Links

• relates to: HBASE-16658 Optimize UTF8 string/byte conversions