Marshall Schor created UIMA-4281:
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Summary: Gradually shrink internal core arrays on reset actions
Key: UIMA-4281
URL: https://issues.apache.org/jira/browse/UIMA-4281
Project: UIMA
Issue Type: Improvement
Components: Core Java Framework
Reporter: Marshall Schor
Priority: Minor
Fix For: 2.7.1SDK
Many internal core data structures composed of arrays (typically of ints)
expand as needed while running. When a reset event occurs (e.g., cas.reset()),
many of these are cleared, but not "shrunk". So the effect of running, say,
one Document which is very large might cause many internal data structures to
expand, and from then on consume potentially large but unused space.
This isn't too bad an issue with modern OSs; except for movement in the heap,
it would be expected that the pages containing the unused space would gradually
be paged out.
Nevertheless, it would be good to gradually shrink these spaces back down after
some peak. The shrinkage should be gradual, to avoid needing to expand the
arrays too often. I think a good rule of thumb would be to remember one
previous size, and to shrink only if both previous sizes were small enough to
be contained in 1 size shrinkage.
This should reduce oscillating back and forth around a particular size, while
recovering space over many "resets" from an early abnormal expansion.
I'm thinking that the 1 size shrinkage algorithm should run the expansion
algorithm backwards - that is, in many of our data structures, expand by
doubling up to some switch point, and then expand linearly by adding.
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