[HADOOP-15564] Classloading Shell should not run a subprocess

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.0.0
• Component/s: util
• Assignee: Unassigned
• Reporter: Todd Lipcon
• Created: 26/Jun/18 23:57
• Updated: 26/Jun/18 23:57

Description

The 'Shell' class has a static member isSetsidSupported which, in order to initialize, forks out a subprocess. Various other parts of the code reference Shell.WINDOWS. For example, the StringUtils class has such a reference. This means that, during startup, a seemingly fast call like Configuration.getBoolean() ends up class-loading StringUtils, which class-loads Shell, which forks out a subprocess. I couldn't measure any big improvement by fixing this, but seemed surprising to say the least.