[HADOOP-15551] Avoid use of Java8 streams in Configuration.addTags

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.0
• Fix Version/s: 3.2.0
• Component/s: performance
• Labels: pull-request-available
• Target Version/s: 3.2.0
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 20/Jun/18 19:38
• Updated: 01/Sep/20 12:25
• Resolved: 20/Jun/18 23:44

Description

Configuration.addTags oddly uses Arrays.stream instead of a more conventional mechanism. When profiling a simple program that uses Configuration, I found that addTags was taking tens of millis of CPU to do very little work the first time it's called, accounting for ~8% of total profiler samples in my program.

[9] 4.52% 253 self: 0.00% 0 java/lang/invoke/MethodHandleNatives.linkCallSite
[9] 3.71% 208 self: 0.00% 0 java/lang/invoke/MethodHandleNatives.linkMethodHandleConstant

I don't know much about the implementation details of the Streams stuff, but it seems it's probably meant more for cases with very large arrays or somesuch. Switching to a normal Set.addAll() call eliminates this from the profile.

Issue Links

• links to: GitHub Pull Request #2265