gistfile1.txt

package com.github.srvaroa.jmh;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;

import java.util.concurrent.TimeUnit;

@State(Scope.Benchmark)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
@Warmup(iterations = 4)
@Fork(value = 5, jvmArgsAppend = {"-XX:-UseBiasedLocking", "-XX:BiasedLockingStartupDelay=0"})
public class BiasedLockingBenchmark {

    int unsafeCounter = 0;
    Object withIdHash;
    Object withoutIdHash;

    @Setup
    public void setup() {
        withIdHash = new Object();
        withoutIdHash = new Object() {
            @Override
            public int hashCode() {
                return 1;
            }
        };
        withIdHash.hashCode();
        withoutIdHash.hashCode();
    }

    @Benchmark
    public void withIdHash(Blackhole bh) {
        synchronized(withIdHash) {
            bh.consume(unsafeCounter++);
        }
    }

    @Benchmark
    public void withoutIdHash(Blackhole bh) {
        synchronized(withoutIdHash) {
            bh.consume(unsafeCounter++);
        }
    }

    @Benchmark
    @Threads(2)
    public void withoutIdHashContended(Blackhole bh) {
        synchronized(withoutIdHash) {
            bh.consume(unsafeCounter++);
        }
    }

    @Benchmark
    @Threads(2)
    public void withIdHashContended(Blackhole bh) {
        synchronized(withIdHash) {
            bh.consume(unsafeCounter++);
        }
    }

}

withIdHashContended and withoutIdHashContended are exeactly same

Thanks! fixed