Performance of nextInt(int) in BitsStreamGenerator can be improved
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Key: MATH-642
URL: https://issues.apache.org/jira/browse/MATH-642
Project: Commons Math
Issue Type: Improvement
Affects Versions: 2.2, 2.1, 2.0
Reporter: Phil Steitz
Priority: Minor
Fix For: 3.0
The code used to implement this method in Apache Harmony's Random class
performs better with the Mersenne and Well generators as bit sources as well as
the JDK generator. Here are some benchmark testing results ("orginal" is the
current code):
nextInt(10) comparison - JDK generator (runs per timed block: 100000, timed
blocks: 1000)
original value = 10: 5.417883e-05 (1.010215e-05) ms
harmony value = 10: 3.808923e-05 (1.090630e-05) ms
nextInt(100) comparison - JDK generator (runs per timed block: 100000, timed
blocks: 1000)
original value = 100: 4.602311e-05 (5.075280e-06) ms
harmony value = 100: 3.771343e-05 (5.836102e-06) ms
nextInt(10000) comparison - JDK generator (runs per timed block: 100000, timed
blocks: 1000)
original value = 10000: 5.317242e-05 (5.527069e-06) ms
harmony value = 10000: 3.676283e-05 (5.062836e-06) ms
nextInt(32) comparison - JDK generator (runs per timed block: 100000, timed
blocks: 1000)
original value = 32: 6.225222e-05 (1.143497e-05) ms
harmony value = 32: 3.875278e-05 (6.099984e-06) ms
nextInt(10) comparison - Well1024a (runs per timed block: 100000, timed blocks:
1000)
original value = 10: 4.365601e-05 (1.013942e-05) ms
harmony value = 10: 4.141704e-05 (1.778676e-05) ms
nextInt(100) comparison - Well1024a (runs per timed block: 100000, timed
blocks: 1000)
original value = 100: 3.579893e-05 (4.670346e-06) ms
harmony value = 100: 3.474323e-05 (5.273507e-06) ms
nextInt(10000) comparison - Well1024a (runs per timed block: 100000, timed
blocks: 1000)
original value = 10000: 4.431216e-05 (5.654163e-06) ms
harmony value = 10000: 3.440765e-05 (4.282874e-06) ms
nextInt(32) comparison - Well1024a (runs per timed block: 100000, timed blocks:
1000)
original value = 32: 5.080220e-05 (7.276901e-06) ms
harmony value = 32: 2.958944e-05 (1.091995e-05) ms
nextInt(10) comparison - MersenneTwister (runs per timed block: 100000, timed
blocks: 1000)
original value = 10: 4.365044e-05 (1.284578e-05) ms
harmony value = 10: 3.199023e-05 (7.170367e-06) ms
nextInt(100) comparison - MersenneTwister (runs per timed block: 100000, timed
blocks: 1000)
original value = 100: 3.488505e-05 (4.822188e-06) ms
harmony value = 100: 3.145389e-05 (5.290716e-06) ms
nextInt(10000) comparison - MersenneTwister (runs per timed block: 100000,
timed blocks: 1000)
original value = 10000: 4.468017e-05 (1.086927e-05) ms
harmony value = 10000: 3.274545e-05 (2.059499e-05) ms
nextInt(32) comparison - MersenneTwister (runs per timed block: 100000, timed
blocks: 1000)
original value = 32: 5.129467e-05 (6.652250e-06) ms
harmony value = 32: 2.569880e-05 (8.063487e-06) ms
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