[HADOOP-10381] Support unit suffix in the configuration values

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.3.0
• Component/s: conf
• Assignee: Unassigned
• Reporter: Mingjiang Shi
• Created: 04/Mar/14 08:07
• Updated: 05/Mar/14 09:42
• Resolved: 05/Mar/14 09:42

Description

Background
Currently, most configuration values implicitly indicate the unit, for example:

• dfs.namenode.delegation.key.update-interval, the unit is milliseconds,
• dfs.ha.log-roll.period, the unit is seconds
• dfs.datanode.du.reserved, the unit is bytes

This causes a few inconveniences
1. When modify a configuration file, one need to refer to the document to find out the expected unit, convert from the human readable unit to the expect unit. Otherwise, wrong value may be configured.
2. While reviewing the configuration file, it'll take some time to figure out the human readable size of a large number. For example, 134217728 is actually 128MB

Proposal
For any space or time related configurations, it should allow include the unit suffix, for example:

• space related units: 64kb, 128mb, 1gb
• time related units: 1000ms, 1min, 60sec, 1hour

If no unit suffix is given, the default unit for the configuration item is used.

Issue Links

• duplicates: HADOOP-7910 add configuration methods to handle human readable size values
• duplicates: HADOOP-8608 Add Configuration API for parsing time durations