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8277175: Add a parallel multiply method to BigInteger

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Reviewed-by: psandoz
This commit is contained in:
Dr Heinz M. Kabutz 2022-02-11 18:49:04 +00:00 • committed by Paul Sandoz
parent 0786ddb471
commit 83ffbd2e7a
4 changed files with 601 additions and 19 deletions
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61
test/micro/org/openjdk/bench/java/math/BigIntegerParallelMultiply.java Normal file
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package org.openjdk.bench.java.math;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import java.math.BigInteger;
import java.util.concurrent.TimeUnit;
import java.util.function.BinaryOperator;
/**
* Benchmark for checking performance difference between
* sequential and parallel multiply methods in BigInteger,
* using a large Fibonacci calculation of up to n = 100 million.
*
* @author Heinz Kabutz, heinz@javaspecialists.eu
*/
@BenchmarkMode(Mode.SingleShotTime)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
@Fork(value = 2)
@Warmup(iterations = 2)
@Measurement(iterations = 2) // only 2 iterations because each one takes very long
@State(Scope.Thread)
public class BigIntegerParallelMultiply {
private static BigInteger fibonacci(int n, BinaryOperator<BigInteger> multiplyOperator) {
if (n == 0) return BigInteger.ZERO;
if (n == 1) return BigInteger.ONE;
int half = (n + 1) / 2;
BigInteger f0 = fibonacci(half - 1, multiplyOperator);
BigInteger f1 = fibonacci(half, multiplyOperator);
if (n % 2 == 1) {
BigInteger b0 = multiplyOperator.apply(f0, f0);
BigInteger b1 = multiplyOperator.apply(f1, f1);
return b0.add(b1);
} else {
BigInteger b0 = f0.shiftLeft(1).add(f1);
return multiplyOperator.apply(b0, f1);
}
}
@Param({"1000000", "10000000", "100000000"})
private int n;
@Benchmark
public void multiply() {
fibonacci(n, BigInteger::multiply);
}
@Benchmark
public void parallelMultiply() {
fibonacci(n, BigInteger::parallelMultiply);
}
}