MaxTest

MaxTest.java

package test;

import java.util.concurrent.TimeUnit;
import java.util.stream.*;
import java.util.*;
import java.util.regex.*;

import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.annotations.*;
 
@Warmup(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Fork(3)
@State(Scope.Benchmark)
public class MaxTest {
  @Param({"500000"})
  private int n;

  int[] ints;

  @Setup
  public void setUp() {
    ints = new Random(1).ints(n).toArray();
  }

  @Benchmark
  public int loop() {
    int[] a = ints;
    int e = ints.length;
    int m = Integer.MIN_VALUE;
    for(int i=0; i<e; i++)
      if(a[i] > m) m = a[i];
    return m;
  }

  @Benchmark
  public int stream() {
    return Arrays.stream(ints).reduce(Integer.MIN_VALUE, Math::max);
  }
}

results.txt

# JMH 1.11.2 (released 42 days ago)
# VM version: JDK 1.8.0_45, VM 25.45-b02
...
Benchmark          (n)  Mode  Cnt    Score   Error  Units
MaxTest.loop    500000  avgt   30  200.462 ± 0.534  us/op
MaxTest.stream  500000  avgt   30  596.783 ± 6.152  us/op