PoolBenchmark.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using OrleansBenchmarks.Serialization;

namespace OrleansBenchmarks
{
    using BenchmarkDotNet.Attributes;

    [Config(typeof(SerializationBenchmarkConfig))]
    public class PoolBenchmark
    {
        private readonly ConcurrentBag<StringBuilder> concurrentBag = new ConcurrentBag<StringBuilder>();

        private readonly ThreadLocal<List<StringBuilder>> stackPool = new ThreadLocal<List<StringBuilder>>(() => new List<StringBuilder>());

        [ThreadStatic]
        private static List<StringBuilder> tsPool;

        private static List<StringBuilder> GetThreadStaticPool() => tsPool ?? (tsPool = new List<StringBuilder>());

        [Setup]
        public void Setup()
        {
            ReturnListPool(GetListPool());
            ReturnBag(GetBag());
            ReturnThreadStaticListPool(GetThreadStaticListPool());
        }

        private StringBuilder GetListPool()
        {
            var pool = stackPool.Value;
            if (pool.Count > 0)
            {
                var val = pool[pool.Count - 1];
                pool.RemoveAt(pool.Count - 1);
                return val;
            }

            return new StringBuilder();
        }

        private void ReturnListPool(StringBuilder value)
        {
            stackPool.Value.Add(value);
        }
        private StringBuilder GetThreadStaticListPool()
        {
            var pool = GetThreadStaticPool();
            if (pool.Count > 0)
            {
                var last = pool.Count - 1;
                var val = pool[last];
                pool.RemoveAt(last);
                return val;
            }

            return new StringBuilder();
        }

        private void ReturnThreadStaticListPool(StringBuilder value)
        {
            GetThreadStaticPool().Add(value);
        }

        private StringBuilder GetBag()
        {
            StringBuilder result;
            if (concurrentBag.TryTake(out result)) return result;
            return new StringBuilder();
        }

        private void ReturnBag(StringBuilder value)
        {
            concurrentBag.Add(value);
        }
        
        [Benchmark]
        public void ConcurrentBagPool()
        {
            var val = GetBag();
            ReturnBag(val);
        }

        [Benchmark]
        public void ThreadLocalListPool()
        {
            var val = GetListPool();
            ReturnListPool(val);
        }

        [Benchmark]
        public void ThreadStaticListPool()
        {
            var val = GetThreadStaticListPool();
            ReturnThreadStaticListPool(val);
        }
    }
}

// * Summary *

Host Process Environment Information:
BenchmarkDotNet.Core=v0.9.9.0
OS=Microsoft Windows NT 6.2.9200.0
Processor=Intel(R) Xeon(R) CPU E3-1230 v5 3.40GHz, ProcessorCount=8
Frequency=3328121 ticks, Resolution=300.4698 ns, Timer=TSC
CLR=MS.NET 4.0.30319.42000, Arch=32-bit RELEASE
GC=Non-concurrent Server
JitModules=clrjit-v4.6.2012.0

Type=PoolBenchmark  Mode=Throughput

               Method |      Median |    StdDev | Gen 0 | Gen 1 | Gen 2 | Bytes Allocated/Op |
--------------------- |------------ |---------- |------ |------ |------ |------------------- |
    ConcurrentBagPool | 135.7436 ns | 1.6784 ns | 17.00 |     - |     - |               8.02 |
  ThreadLocalListPool |  41.3818 ns | 0.4723 ns |     - |     - |     - |               0.00 |
 ThreadStaticListPool |  32.8183 ns | 0.8218 ns |     - |     - |     - |               0.00 |