FastCache.Cached 1.3.1

There is a newer version of this package available.
See the version list below for details.
dotnet add package FastCache.Cached --version 1.3.1                
NuGet\Install-Package FastCache.Cached -Version 1.3.1                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="FastCache.Cached" Version="1.3.1" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add FastCache.Cached --version 1.3.1                
#r "nuget: FastCache.Cached, 1.3.1"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install FastCache.Cached as a Cake Addin
#addin nuget:?package=FastCache.Cached&version=1.3.1

// Install FastCache.Cached as a Cake Tool
#tool nuget:?package=FastCache.Cached&version=1.3.1                


<p><img src="" width="180" height="180" align="right" /></p>

CI/CD nuget

The fastest cache library written in C# for items with set expiration time. Easy to use, thread-safe and light on memory.

Optimized to scale from dozens to millions of items. Features lock-free reads and writes, allocation-free reads and automatic eviction.

Credit to Vladimir Sadov for his implementation of NonBlocking.ConcurrentDictionary which is used as an underlying store.

Quick start

dotnet add package FastCache.Cached or Install-Package FastCache.Cached

Get cached value or save a new one with expiration of 60 minutes

public FinancialReport GetReport(int month, int year)
  if (Cached<FinancialReport>.TryGet(month, year, out var cached))
    return cached.Value;

  var report = // Expensive computation: retrieve data and calculate report

  return cached.Save(report, TimeSpan.FromMinutes(60));

Wrap and cache the result of a regular method call

var report = Cached.GetOrCompute(month, year, GetReport, TimeSpan.FromMinutes(60));

Or an async one

// For methods that return Task<T> or ValueTask<T>
var report = await Cached.GetOrCompute(month, year, GetReportAsync, TimeSpan.FromMinutes(60));

Save the value to cache but only if the cache size is below limit

public FinancialReport GetReport(int month, int year)
  if (Cached<FinancialReport>.TryGet(month, year, out var cached))
    return cached.Value;

  return cached.Save(report, TimeSpan.FromMinutes(60), limit: 2_500_000);
// GetOrCompute with maximum cache size limit.
// RAM is usually plenty but what if the user runs Chrome?
var report = Cached.GetOrCompute(month, year, GetReport, TimeSpan.FromMinutes(60), limit: 2_500_000);

Add new data without accessing cache item first (e.g. loading a large batch of independent values to cache)

using FastCache.Extensions;
foreach (var ((month, year), report) in reportsResultBatch)
  report.Cache(month, year, TimeSpan.FromMinutes(60));

Store common type (string) in a shared cache store (other users may share the cache for the same parameter type, this time it's int)

// GetOrCompute<...V> where V is string.
// To save some other string for the same 'int' number simultaneously, look at the option below :)
var userNote = Cached.GetOrCompute(userId, GetUserNoteString, TimeSpan.FromMinutes(5));

Or in a separate one by using value object (Recommended)

readonly record struct UserNote(string Value);

// GetOrCompute<...V> where V is UserNote
var userNote = Cached.GetOrCompute(userId, GetUserNote, TimeSpan.FromMinutes(5));
// This is how it looks for TryGet
if (Cached<UserNote>.TryGet(userId, out var cached))
  return cached.Value;
return cached.Save(userNote, TimeSpan.FromMinutes(5));

Features and design philosophy

  • In-memory cache for items with expiration time and automatic eviction
  • Little to no ceremony - no need to configure or initialize, just add the package and you are ready to go. Behavior can be further customized via env variables
  • Focused design allows to reduce memory footprint per item and minimize overhead via inlining and static dispatch
  • High performance and scaling covering both simplest applications and highly loaded services. Can handle 1-100M+ items with O(1) read/write time and up to O(n~) memory cost/cpu time cost for full eviction
  • Lock-free and wait-free reads/writes of cached items. Performance will improve with threads, data synchronization cost is minimal thanks to NonBlocking.ConcurrentDictionary
  • Multi-key store access without collisions between key types. Collisions are avoided by statically dispatching on the composite key type signature e.g. (string, CustomEnum, int) together with the type of cached value - composite keys are structurally evaluated for equality, different combinations will correspond to different cache items
  • Handles timezone/DST updates on most platforms by relying on system uptime timestamp for item expiration - Environment.TickCount64 which is also significantly faster than DateTime.UtcNow


BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000
AMD Ryzen 7 5800X, 1 CPU, 16 logical and 8 physical cores
.NET 6.0.5 (6.0.522.21309), X64 RyuJIT

TLDR: FastCache.Cached vs Microsoft.Extensions.Caching.Memory.MemoryCache

Library Lowest read latency Read throughput (M/1s) Lowest write latency Write throughput (M/1s) Cost per item Cost per 10M items
FastCache.Cached 15.63 ns 114-288M MT / 9-72M ST 33.75 ns 39-81M MT / 6-31M ST 40 B 381 MB
MemoryCache 56.93 ns 41-46M MT / 4-10M ST 203.32 ns 11-26M MT / 2-6M ST 224 B 2,136 MB
CacheManager 87.54 ns N/A ~436.85 ns N/A MT / 1.5-5M ST (+alloc)360 B 1,602 MB

+CachedRange.Save(ReadOnlySpan<(K, V)>) provides parallelized bulk writes out of box

++CacheManager doesn't have read throughput results because test suite would take too long to run to include CacheManager and LazyCache. Given higher CPU usage by CacheManager and higher RAM usage by LazyCache it is reasonable to assume they would score lower and scale worse due to higher number of locks

Read/Write lowest achievable latency

Method Mean Error StdDev Median Ratio Gen 0 Allocated
Get: FastCache.Cached 15.63 ns 0.452 ns 1.334 ns 14.61 ns 1.00 - -
Get: MemoryCache 56.93 ns 1.179 ns 1.904 ns 55.73 ns 3.68 - -
Get: CacheManager* 87.54 ns 1.751 ns 2.454 ns 89.32 ns 5.68 - -
Get: LazyCache 73.43 ns 1.216 ns 1.138 ns 73.25 ns 4.71 - -
Set: FastCache.Cached 33.75 ns 0.861 ns 2.539 ns 31.92 ns 2.18 0.0024 40 B
Set: MemoryCache 203.32 ns 4.033 ns 6.956 ns 199.77 ns 13.23 0.0134 224 B
Set: CacheManager* 436.85 ns 8.729 ns 19.160 ns 433.97 ns 28.10 0.0215 360 B
Set: LazyCache 271.56 ns 5.428 ns 7.785 ns 274.19 ns 17.58 0.0286 480 B

Read throughput detailed

Method Count Reads/1s Mean Error StdDev Ratio
Read(MT): FastCache 1,000 130.97M 7.635 us 0.1223 us 0.1144 us 1.00
Read(ST): FastCache 1,000 72.99M 13.700 us 0.2723 us 0.5562 us 1.78
Read(MT): MemoryCache 1,000 41.35M 24.183 us 1.2907 us 3.7853 us 2.68
Read(ST): MemoryCache 1,000 10.31M 96.943 us 0.9095 us 0.8063 us 12.71
Read(MT): FastCache 100,000 288.66M 346.418 us 5.2196 us 6.6011 us 1.00
Read(ST): FastCache 100,000 28.99M 3,449.865 us 66.4929 us 81.6593 us 9.96
Read(MT): MemoryCache 100,000 46.77M 2,138.400 us 175.2152 us 516.6259 us 6.32
Read(ST): MemoryCache 100,000 4.64M 21,540.964 us 394.9239 us 499.4523 us 62.20
Read(MT): FastCache 1,000,000 114.54M 8,730.009 us 173.8538 us 170.7476 us 1.00
Read(ST): FastCache 1,000,000 9.74M 102,580.795 us 926.3173 us 866.4778 us 11.76
Read(MT): MemoryCache 1,000,000 41.46M 24,114.261 us 369.3612 us 308.4334 us 2.76
Read(ST): MemoryCache 1,000,000 3.92M 254,619.996 us 2,585.3079 us 2,291.8081 us 29.17
Read(MT): FastCache 10,000,000 112.89M 88,584.244 us 1,709.9078 us 1,599.4488 us 1.00
Read(ST): FastCache 10,000,000 9.70M 1,030,431.980 us 9,874.4883 us 9,236.6025 us 11.64
Read(MT): MemoryCache 10,000,000 42.84M 233,410.703 us 2,945.8464 us 2,299.9231 us 2.63
Read(ST): MemoryCache 10,000,000 4.13M 2,421,159.114 us 35,280.8135 us 31,275.5222 us 27.33

Further reading

  • Keys and composite keys performance estimation: Code / Results
  • FastCache.Cached defaults provide highest performance and don't require spending time on finding a way to use API optimally. The design goal is to nudge a developer to use the fastest way to achieve his or her goals while strictly adhering to the principle of "pay for play".
  • Comparison was made with a string-based key. Composite keys supported by FastCache.Cached have additional performance cost. Numeric keys have significantly higher performance in some instances (down to 5ns read latency on x86_64 where K is int or uint and V fits in a single register).
  • *CacheManger documentation suggests using WithMicrosoftMemoryCacheHandle() by default which has terrible performance (and uses obsolete System.Runtime.Caching). We give it a better fighting chance by using WithDictionaryHandle() instead.
  • **CachedRange.Save(ReadOnlyMemory<(K, V)>) (and CachedRange.Save(ReadOnlyMemory<K>, ReadOnlyMemory<V>)) automatically splits the range into slices of 1024 or length / cpu cores elements and saves them in parallel which dramatically improves throughput. This works especially well because the execution flow is lock-free and does not suffer from false sharing of CPU cache lines (except for the adjacent entries at the edges of slices)
  • ***Forced single-threaded execution of CachedRange.Save(ReadOnlyMemory<(K, V)>)
  • Overall, performance stays relatively comparable when downgrading to .NET 5 and decreases further by 15-30% when using .NET Core 3.1 with the difference ratio between libraries staying close to provided above.
  • Non-standard platforms (the ones that aren't CLR based) use DateTime.UtcNow fallback instead of Environment.TickCount64, which will perform slower depending on the platform-specific implementation.
On benchmark data

Throughput saturation means that all necessary data structures are fully available in the CPU cache and branch predictor has learned branch patters of the executed code. This is only possible in scenarios such as items being retrieved or added/updated in a tight loop or very frequently on the same cores. This means that real world performance will not saturate maximum throughput and will be bottlenecked by memory access latency and branch misprediction stalls. As a result, you can expect resulting performance variance of 1-10x min latency depending on hardware and outside factors.

From πŸ‡ΊπŸ‡¦ Ukraine with β™₯️

Product Compatible and additional computed target framework versions.
.NET net5.0 is compatible.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 is compatible.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp3.0 was computed.  netcoreapp3.1 is compatible. 
.NET Standard netstandard2.1 is compatible. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
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