PositionUpdateSystem.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Unity.Jobs.LowLevel;
using Unity.Jobs;
using Unity.Jobs.LowLevel.Unsafe;
using Unity.Collections;
using Unity.Collections.LowLevel;
using Unity.Collections.LowLevel.Unsafe;

public class PositionUpdateSystem : MonoBehaviour
{
    JobHandle handle;
    void Awake()
    {
        JobsUtility.JobWorkerCount = 2;
        Debug.Log(JobsUtility.JobWorkerMaximumCount - 1);
    }

    void OnDestroy()
    {
        handle.Complete();
    }

    void Update()
    {
        handle.Complete();

        var array = new NativeArray<int>(JobsUtility.MaxJobThreadCount, Allocator.TempJob);
        var counter = new NativeArray<int>(1, Allocator.TempJob);

        handle = new CountJob { array = array }.Schedule( 24576, 8 );
        handle = new GatherJob { array = array, counter = counter }.Schedule(handle);
        handle = new LogJob { counter = counter }.Schedule(handle);

        array.Dispose(handle);
        counter.Dispose(handle);

        JobHandle.ScheduleBatchedJobs();
    }

    //[Unity.Burst.BurstCompile]
    struct CountJob : IJobParallelFor 
    {
        [NativeSetThreadIndex]
        int threadIndex;

        [NativeDisableContainerSafetyRestriction]
        public NativeArray<int> array;

        public void Execute(int index)
        {
            var count = array[threadIndex];
            count= count + 1;
            array[threadIndex] = count;
        }
    }

    //[Unity.Burst.BurstCompile]
    struct GatherJob : IJob
    {
        [ReadOnly]
        public NativeArray<int> array;

        [WriteOnly]
        public NativeArray<int> counter;

        public void Execute()
        {
            var count = 0;
            for (int index = 0; index < array.Length; index++)
            {
                count = count + array[index];
            }
            counter[0] = count;
        }
    }

    struct LogJob : IJob
    {
        [ReadOnly]
        public NativeArray<int> counter;

        public void Execute()
        {
            Debug.Log(counter[0]);
        }
    }
}