[HADOOP-15549] Upgrade to commons-configuration 2.1 regresses task CPU consumption

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.2
• Fix Version/s: 3.2.0
• Component/s: metrics
• Target Version/s: 3.1.1
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 20/Jun/18 17:14
• Updated: 16/Mar/20 07:14
• Resolved: 21/Jun/18 17:34

Description

HADOOP-13660 upgraded from commons-configuration 1.x to 2.x. commons-configuration is used when parsing the metrics configuration properties file. The new builder API used in the new version apparently makes use of a bunch of very bloated reflection and classloading nonsense to achieve the same goal, and this results in a regression of >100ms of CPU time as measured by a program which simply initializes DefaultMetricsSystem.

This isn't a big deal for long-running daemons, but for MR tasks which might only run a few seconds on poorly-tuned jobs, this can be noticeable.

Issue Links

• causes: HADOOP-16925 MetricsConfig incorrectly loads the configuration whose value is String list in the properties file
• is duplicated by: HADOOP-16086 Backport HADOOP-15549 to branch-3.1
• is duplicated by: HADOOP-16087 Backport HADOOP-15549 to branch-3.0