Todd Lipcon created HADOOP-15551:
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Summary: Avoid use of Java8 streams in Configuration.addTags
Key: HADOOP-15551
URL: https://issues.apache.org/jira/browse/HADOOP-15551
Project: Hadoop Common
Issue Type: Improvement
Components: performance
Affects Versions: 3.2
Reporter: Todd Lipcon
Assignee: Todd Lipcon
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.
{code}
[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
{code}
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.
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