{"id":27695,"date":"2020-04-23T11:05:20","date_gmt":"2020-04-23T18:05:20","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/dotnet\/?p=27695"},"modified":"2020-04-27T09:12:57","modified_gmt":"2020-04-27T16:12:57","slug":"announcing-net-5-0-preview-3","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/dotnet\/announcing-net-5-0-preview-3\/","title":{"rendered":"Announcing\u00a0.NET\u00a05.0\u00a0Preview\u00a03"},"content":{"rendered":"<p>Today, we&#8217;re releasing .NET 5.0 Preview 3. It contains a set of new features and performance improvements. We&#8217;re continuing to work on the bigger features that will define the 5.0 release. The <a href=\"https:\/\/devblogs.microsoft.com\/dotnet\/announcing-net-5-0-preview-1\/\" rel=\"nofollow\">.NET 5.0 Preview 1 post<\/a> covers what we are planning on building for .NET 5.0. Please take a look at the post and the <a href=\"https:\/\/github.com\/dotnet\/designs\">dotnet\/designs<\/a> repository and share any feedback you have. And, of course, please install Preview 3, and test your workloads with it.<\/p>\n<p>You can <a href=\"https:\/\/dotnet.microsoft.com\/download\/dotnet-core\/5.0\" rel=\"nofollow\">download .NET 5.0 Preview 3<\/a>, for Windows, macOS, and Linux:<\/p>\n<ul>\n<li><a href=\"https:\/\/dotnet.microsoft.com\/download\/dotnet-core\/5.0\" rel=\"nofollow\">.NET 5.0 Preview 3 and Runtime<\/a><\/li>\n<li><a href=\"https:\/\/hub.docker.com\/_\/microsoft-dotnet-core\" rel=\"nofollow\">Docker images<\/a><\/li>\n<li><a href=\"https:\/\/snapcraft.io\/dotnet-sdk\" rel=\"nofollow\">Snap installer<\/a><\/li>\n<\/ul>\n<p><a href=\"https:\/\/devblogs.microsoft.com\/aspnet\/asp-net-core-updates-in-net-5-preview-3\/\">ASP.NET Core<\/a> and <a href=\"https:\/\/devblogs.microsoft.com\/dotnet\/announcing-entity-framework-core-5-0-preview-3\/\">EF Core<\/a> are also being released today.<\/p>\n<p>You need to use Visual Studio 2019 16.6 to use .NET 5.0. Install the latest version of the <a href=\"https:\/\/code.visualstudio.com\/Docs\/languages\/csharp\" rel=\"nofollow\">C# extension<\/a>, to use .NET 5.0 with Visual Studio Code. .NET 5.0 isn&#8217;t yet supported with Visual Studio for Mac.<\/p>\n<p>Release notes:<\/p>\n<ul>\n<li><a href=\"https:\/\/github.com\/dotnet\/core\/blob\/master\/release-notes\/5.0\/preview\/5.0.0-preview.3.md\">.NET 5.0 Preview 3 release notes<\/a><\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/core\/blob\/master\/release-notes\/5.0\/5.0-known-issues.md\">.NET 5.0 known issues<\/a><\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/core\/issues\/4607\">GitHub tracking issue<\/a><\/li>\n<\/ul>\n<p>Let&#8217;s look at some of the improvements in Preview 3.<\/p>\n<h3><a id=\"user-content-code-quality-improvements-in-ryujit\" class=\"anchor\" href=\"#code-quality-improvements-in-ryujit\" aria-hidden=\"true\"><\/a>Code quality improvements in RyuJIT<\/h3>\n<p>Every release includes a set of changes that improve the machine code that the JIT generates (we call this &#8220;code quality&#8221;). Better code quality means better application performance.<\/p>\n<ul>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/33749\">Vectorise BitArray for ARM64 &#8211; dotnet\/runtime #33749<\/a> &#8212; The <a href=\"https:\/\/docs.microsoft.com\/dotnet\/api\/system.collections.bitarray?view=netframework-4.8\" rel=\"nofollow\">BitArray class<\/a> was updated to include a <a href=\"https:\/\/github.com\/dotnet\/runtime\/blob\/8511b5b9cc957ce824fc88c0780249fc0edbef15\/src\/libraries\/System.Collections\/src\/System\/Collections\/BitArray.cs#L181\">hardware-accelerated implementation for ARM64<\/a> using <a href=\"https:\/\/github.com\/dotnet\/runtime\/tree\/master\/src\/libraries\/System.Private.CoreLib\/src\/System\/Runtime\/Intrinsics\/Arm\">ARM64 intrinisics<\/a>. The <a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/33749#issuecomment-603597689\">performance improvements<\/a> for BitArray are very significant. Credit to <a href=\"https:\/\/github.com\/Gnbrkm41\">@Gnbrkm41<\/a>.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/32969\">Implement simple version of On Stack Replacement (OSR) &#8211; dotnet\/runtime #32969<\/a>. <a href=\"https:\/\/github.com\/dotnet\/runtime\/blob\/master\/docs\/design\/features\/OnStackReplacement.md\">On-stack replacement (OSR)<\/a> is a new capability that allows the code executed by currently running methods to be changed in the middle of method execution, while those methods are active &#8220;on stack&#8221;. This feature is currently experimental and opt-in (on x64), and targeted at improving the more challenging performance characteristics of tiered compilation. Please try it out and give us feedback.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/32270\">Dynamic generic dictionary expansion feature dotnet\/runtime #32270<\/a> &#8211; Some (maybe many) uses of generics now have better performance (<a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/32270#issuecomment-586459130\">initial performance findings<\/a>), based on improving the implementation of low-level (native code) dictionaries used by the runtime to store information about generic types and methods. See <a href=\"https:\/\/github.com\/dotnet\/runtime\/issues\/11971#issuecomment-462183168\">Perf: Collection Count() is Slower in Core than the CLR<\/a> for more information. Credit to <a href=\"https:\/\/github.com\/RealDotNetDave\">@RealDotNetDave<\/a> for the bug report.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/31993\">Implement Vector.Ceiling \/ Vector.Floor dotnet\/runtime #31993<\/a> &#8211; Implement Vector.Ceiling \/ Vector.Floor using x64 and ARM64 intrinsics, per <a href=\"https:\/\/github.com\/dotnet\/runtime\/issues\/20509\">API proposal<\/a>. Credit to <a href=\"https:\/\/github.com\/Gnbrkm41\">@Gnbrkm41<\/a>.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/34221\">JIT: allow CORINFO_HELP_READYTORUN_GENERIC_HANDLE to be optimized dotnet\/runtime #34221<\/a>. Improves code quality for generics in Ready2Run images.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/33004\">JIT: enable tail calls and copy omission for implicit byref structs #33004<\/a>. Improves code quality for structs as arguments in &#8220;tail call&#8221; position calls.<\/li>\n<\/ul>\n<h3><a id=\"user-content-systemtextjson-improvements\" class=\"anchor\" href=\"#systemtextjson-improvements\" aria-hidden=\"true\"><\/a>System.Text.Json improvements<\/h3>\n<ul>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/655\">Add support for preserve references on JSON dotnet\/runtime #655<\/a> &#8211; <a href=\"https:\/\/github.com\/dotnet\/runtime\/issues\/29900\">Enables <code>ReferenceLoopHandling<\/code><\/a>, which is one of the key features of JSON.NET serialization.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/33459\">Add new System.Net.Http.Json project\/namespace dotnet\/runtime #33459<\/a> &#8211; Adds <a href=\"https:\/\/github.com\/dotnet\/runtime\/issues\/32937\">new extension methods for HttpClient that allow serialization from\/to JSON<\/a>.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/33444\">Add <code>JsonConstructor<\/code> and support for deserializing with parameterized ctors dotnet\/runtime #33444<\/a> &#8212; Adds support for immutable classes and structs to JsonSerializer.<\/li>\n<li><a href=\"https:\/\/github.com\/dotnet\/runtime\/pull\/34049\">Add JsonIgnoreCondition &amp; per-property ignore logic #34049<\/a> &#8211; Adds support for null value handling, which is another feature of JSON.NET serialization.<\/li>\n<\/ul>\n<h3><a id=\"user-content-net-sdk-support-for-net-framework-assemblies\" class=\"anchor\" href=\"#net-sdk-support-for-net-framework-assemblies\" aria-hidden=\"true\"><\/a>.NET SDK Support for .NET Framework Assemblies<\/h3>\n<p>The <a href=\"https:\/\/github.com\/dotnet\/sdk\/issues\/4009\">.NET SDK will now auto-reference<\/a> the <a href=\"https:\/\/www.nuget.org\/packages\/Microsoft.NETFramework.ReferenceAssemblies\/\" rel=\"nofollow\">Microsoft.NETFramework.ReferenceAssemblies<\/a> NuGet package given a .NET Framework target framework in a project file. This change enables building .NET Framework projects on a machine without the required .NET Framework targeting pack installed. This improvement is specific to targeting packs, and doesn&#8217;t account for other dependencies that a project may have.<\/p>\n<h3><a id=\"user-content-closing\" class=\"anchor\" href=\"#closing\" aria-hidden=\"true\"><\/a>Closing<\/h3>\n<p>Please take a moment to try out Preview 3, possibly in a container, a VM. We&#8217;d like your feedback on the quality of the release. There is a lot more coming, over the next several months, leading up a November release.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Today, we&#8217;re releasing .NET 5.0 Preview 3. It contains a set of new features and performance improvements. We&#8217;re continuing to work on the bigger features that will define the 5.0 release. The .NET 5.0 Preview 1 post covers what we are planning on building for .NET 5.0. Please take a look at the post and [&hellip;]<\/p>\n","protected":false},"author":336,"featured_media":58792,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[685],"tags":[],"class_list":["post-27695","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-dotnet"],"acf":[],"blog_post_summary":"<p>Today, we&#8217;re releasing .NET 5.0 Preview 3. It contains a set of new features and performance improvements. We&#8217;re continuing to work on the bigger features that will define the 5.0 release. The .NET 5.0 Preview 1 post covers what we are planning on building for .NET 5.0. Please take a look at the post and [&hellip;]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/posts\/27695","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/users\/336"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/comments?post=27695"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/posts\/27695\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/media\/58792"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/media?parent=27695"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/categories?post=27695"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/dotnet\/wp-json\/wp\/v2\/tags?post=27695"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}