Update "What's new in ASP.NET Core in .NET 10" for .NET 10 Preview 6

[danroth27]

Description

Update "What's new in ASP.NET Core in .NET 10" for .NET 10 Preview 6.

Page URL

https://learn.microsoft.com/en-us/aspnet/core/release-notes/aspnetcore-10.0?view=aspnetcore-9.0

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/release-notes/aspnetcore-10.0.md

Document ID

a7ad4b01-2333-32d8-b759-e044edfb9102

Platform Id

2f8fb8ab-5309-0a77-987a-c867c6517d2b

Article author

@Rick-Anderson

Metadata

• ID: a7ad4b01-2333-32d8-b759-e044edfb9102
• PlatformId: 2f8fb8ab-5309-0a77-987a-c867c6517d2b
• Service: aspnet-core
• Sub-service: release-notes

Related Issues

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Associated WorkItem - 442589

[BrennanConroy]

Automatic eviction from memory pool

#35661 WN
#35662 HTTP.sys docs
#35663 Kestrel docs

The memory pools used by Kestrel (IIS and Http.Sys too) now automatically evict memory blocks when the application is idle or under less load, helping applications use resources more efficiently.

Why it matters:
Previously, memory allocated by the pool would remain reserved, even when not in use. With this enhancement, when the app is idle for a period of time memory is now released back to the system, reducing overall memory usage and helping applications stay responsive under varying workloads.

How to use:
No action is needed to benefit from this feature. Memory eviction is handled automatically by the framework.

There are also metrics added to the default memory pool used by our server implementations. The new metrics are under the name "Microsoft.AspNetCore.MemoryPool". See https://learn.microsoft.com/aspnet/core/log-mon/metrics/metrics?view=aspnetcore-9.0 for general information on what metrics are and how to use them.

We have also enabled the ability to use:

public class MyBackgroundService : BackgroundService
{
    private readonly MemoryPool<byte> _memoryPool;

    public MyBackgroundService(IMemoryPoolFactory<byte> factory)
    {
        _memoryPool = factory.CreatePool();
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                await Task.Delay(20, stoppingToken);
                // do work that needs memory
                var rented = _memoryPool.Rent(100);
                rented.Dispose();
            }
            catch (OperationCanceledException)
            {
                return;
            }
        }
    }
}

or replace the memory pool being used:

services.AddSingleton<IMemoryPoolFactory<byte>, CustomMemoryPoolFactory>();

public class CustomMemoryPoolFactory : IMemoryPoolFactory<byte>
{
    public MemoryPool<byte> Create()
    {
        // Return a custom MemoryPool implementation or the default.
        return MemoryPool<byte>.Shared;
    }
}