6 methods of multithread Dictionary manipulation benchmark

DictionaryPerformanceUnitTest.cs

using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

//  66ms: Dictionary with lock()
//  78ms: Dictionary with ReaderWriterLockSlim
// 128ms: ConcurrentDictionary (with Add if not exists)
// 137ms: ConcurrentDictionary (always setting)
// 434ms: DictionaryWithReaderWriterLock
// 535ms: DictionaryWithSemaphoreSlim (no-slim version is system wide... no, thank you)

namespace WebScaleFX.UnitTest
{
	[TestClass]
	public class DictionaryPerformance
	{
		[TestMethod]
		public void DictionaryWithLock() // 66ms
		{
			var dictionary = new Dictionary<int, int>();
			var random = new Random();

			Parallel.For(0, 1000000, c =>
			{
				var index = random.Next(0, 1000);

				lock(dictionary)
				{
					dictionary.TryGetValue(index, out var value);
					value++;
					dictionary[index] = value;
				}
			});
		}

		[TestMethod]
		public void DictionaryWithReaderWriterLockSlim() // 78ms
		{
			var dictionary = new Dictionary<int, int>();
			var locker = new ReaderWriterLockSlim();
			var random = new Random();

			Parallel.For(0, 1000000, c =>
			{
				var index = random.Next(0, 1000);

				locker.EnterWriteLock();
				dictionary.TryGetValue(index, out var value);
				value++;
				dictionary[index] = value;
				locker.ExitWriteLock();
			});
		}

		[TestMethod]
		public void ConcurrentDictionaryAdd() // 128ms
		{
			var dictionary = new ConcurrentDictionary<int, int>();
			var random = new Random();

			Parallel.For(0, 1000000, c =>
			{
				var index = random.Next(0, 1000);

				var exists = dictionary.TryGetValue(index, out var value);

				value++;

				if(exists)
				{
					dictionary[index] = value;
				}
				else
				{
					dictionary.TryAdd(index, value);
				}
			});
		}

		[TestMethod]
		public void ConcurrentDictionarySet() // 137ms
		{
			var dictionary = new ConcurrentDictionary<int, int>();
			var random = new Random();

			Parallel.For(0, 1000000, c =>
			{
				var index = random.Next(0, 1000);

				dictionary.TryGetValue(index, out var value);
				value++;
				dictionary[index] = value;
			});
		}

		[TestMethod]
		public void DictionaryWithReaderWriterLock() // 434ms
		{
			var dictionary = new Dictionary<int, int>();
			var locker = new ReaderWriterLock();
			var random = new Random();

			Parallel.For(0, 1000000, c =>
			{
				var index = random.Next(0, 1000);

				locker.AcquireWriterLock(1000);
				dictionary.TryGetValue(index, out var value);
				value++;
				dictionary[index] = value;
				locker.ReleaseWriterLock();
			});
		}

		[TestMethod]
		public void DictionaryWithSemaphoreSlim() // 535ms
		{
			var dictionary = new Dictionary<int, int>();
			var semaphore = new SemaphoreSlim(1, 1);
			var random = new Random();

			Parallel.For(0, 1000000, async c =>
			{
				var index = random.Next(0, 1000);

				await semaphore.WaitAsync();
				dictionary.TryGetValue(index, out var value);
				value++;
				dictionary[index] = value;
				semaphore.Release();
			});
		}
	}
}