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͋ͳͨͱཚ਺ੜ੒ͱ Java ୈेճ #ौ୩java 2015-03-07 @komiya_atsushi

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͓·ͩΕ ʢ͓લ୭Αʁʣ

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,0.*:""UTVTIJ !LPNJZB@BUTVTIJ

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Ad server and machine learning with Java

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Random Number Generator

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java.util.Random

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Random classes provided by JDK

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Random classes provided by JDK • java.util.Random • java.security.SecureRandom • SecureRandom.getInstance("SHA1PRNG")   • java.util.concurrent.ThreadLocalRandom • ThreadLocalRandom.current()

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Random classes provided by commons-math3

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Random classes provided by commons-math3 • MersenneTwister • most popular (?) random number generator • Well44497a • longer period than Mersenne Twister • ISAACRandom • a fast cryptographic pseudo-random number generator

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Random classes provided by commons-math3 • RandomDataGenerator supports sampling from various distributions • Beta / Binomial / Cauchy / ChiSquare / Exponential / F / Gamma / Hypergeometric / Pascal / Poisson / T / Weibull / Zipf • java.util.Random only supports sampling from Gaussian (normal distribution)

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Comparisons

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Concurrency of Random and ThreadLocalRandom

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Concurrency of Random and ThreadLocalRandom 5ISFBE-PDBM3BOEPNJTBXFTPNF

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Latency of 200,000,000 times random number generation

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Latency of 200,000,000 times random number generation .FSTFOOF5XJTUFS JTGBTU 3BOEPNJTOPU GBTU

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Conclusion

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If you need… • high concurrency one • use ThreadLocalRandom • very long-period & high quality one • use Well44497a • long-period & fast one • use MersenneTwister • cryptographically secure one • use SecureRandom

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Thanks! Any questions?

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