Microsoft pushes .NET 9 Preview 6 with a range of improvements

Microsoft has unveiled the sixth preview of its planned .NET 9, a major release of the company’s cross-platform software development framework that brings improvements in areas ranging from code layout to System.Numerics. With .NET 9, the ASP.NET web framework introduces fingerprinting of static web assets, which promises to improve caching behavior and enable faster load times.

Downloadable from dotnet.microsoft.com, .NET 9 Preview 6 was introduced July 15. Code layout improvements stem from the refactoring of the RyuJIT compiler’s flowgraph data structures to remove various restrictions around block ordering and to ingrain execution likelihoods into every control flow change between blocks. Also, investments have been made into ensuring profile data is propagated and maintained as the method’s flowgraph is transformed. This has enabled RyuJIT’s block reordering algorithm to be replaced  with a simpler, more global approach, according to Microsoft.

System.Numerics.BigInteger, which supports representing integer values of essentially arbitrary length, adds an enforced maximum length for BigInteger, which can be no more than (2^31) – 1 (approximately 2.14 billion) bits. The new limit ensures that all APIs are well-behaved and consistent while still allowing numbers far beyond most usage scenarios. System.Diagnostics.Metrics now features a Gauge instrument, which is designed to record non-additive values when changes occur. This can, for example, measure the background noise level, where summing the values from multiple rooms would be nonsensical. The Gauge instrument is a generic type that can record any value type, such as int, double, or decimal.

With .NET 9 Preview 6, ASP.NET Core now will cogenerate fingerprinted versions of static web assets when the app is published. Fingerprinted static web assets contain a unique hash of content in their filename, so they never clash with earlier versions of the file. ASP.NET Core then exposes fingerprinted web assets as endpoints with appropriate cache headers to ensure the content is cached for a long time. Fingerprinting web assets helps ensure that stale assets are not used and enables improved caching behavior for quicker load times. The .NET MAUI (Multiplatform App UI) framework also gets improvements in Preview 6, with updates to project and solution templates, and making sure ImageButton always has a background. Also for .NET MAUI, a memory leak was fixed in ToolbarItem.

A general production release of .NET 9 is expected in November. The first preview arrived in February.