Details
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Type:
Improvement
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Status: Open
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Priority:
Critical
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Resolution: Unresolved
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Affects versions: Release 1.5
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Fix versions: None
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Labels:
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Environment:
Clojure 1.5.1.
Dependencies: criterium
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Approval:Triaged
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Patch:Code
Description
Here's a transcript of the behavior. I don't know for sure that reflection is being done, but the performance penalty (about 1300x) suggests it.
user=> (use 'criterium.core) nil user=> (def b (make-array Double/TYPE 1000 1000)) #'user/b user=> (quick-bench (aget ^"[[D" b 304 175)) WARNING: Final GC required 3.5198021166354323 % of runtime WARNING: Final GC required 29.172288684474303 % of runtime Evaluation count : 63558 in 6 samples of 10593 calls. Execution time mean : 9.457308 µs Execution time std-deviation : 126.220954 ns Execution time lower quantile : 9.344450 µs ( 2.5%) Execution time upper quantile : 9.629202 µs (97.5%) Overhead used : 2.477107 ns
One workaround is to use multiple agets.
user=> (quick-bench (aget ^"[D" (aget ^"[[D" b 304) 175)) WARNING: Final GC required 40.59820310542545 % of runtime Evaluation count : 62135436 in 6 samples of 10355906 calls. Execution time mean : 6.999273 ns Execution time std-deviation : 0.112703 ns Execution time lower quantile : 6.817782 ns ( 2.5%) Execution time upper quantile : 7.113845 ns (97.5%) Overhead used : 2.477107 ns
Cause: The inlined version only applies to arity 2, and otherwise it reflects.
