[MATH-642] Performance of nextInt(int) in BitsStreamGenerator can be improved

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0, 2.1, 2.2
• Fix Version/s: 3.0
• Assignee: Unassigned
• Reporter: Phil Steitz
• Created: 06/Aug/11 04:52
• Updated: 24/Mar/12 16:16
• Resolved: 08/Aug/11 04:23

Description

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