jaredpar

Health Report — dotnet/roslyn / roslyn-CI

Overall Health: 🔴 RED (Critical — Infrastructure Failure + Masked Regression)

Current Status: Helix Infrastructure Instability + Masked Razor Regression

The pipeline remains critically impaired. 7 consecutive main branch failures since the last success (1425328, May 18 2:57 PM PDT). Only 3 out of 25 main builds succeeded in the last 3 days (12% success rate).

Active Problems

jaredpar

Health Report — dotnet/roslyn / roslyn-integration-lsp-CI

Overall Health: 🔴 RED — PIPELINE NON-OPERATIONAL (60+ HOURS)

Current Status:

• PIPELINE DOWN — 0% success rate, 9/9 builds failed, 0 builds attempted in 60+ hours
• Last build: 2026-05-16 07:04 AM PDT
• No new builds since — pipeline disabled or trigger broken
• Builds fail pre-test — no test execution occurs, no timeline data retrievable
• Affected: 9 PRs from 6 different authors were blocked

jaredpar

net472-only UnitTests Projects — .NET Core/Linux Migration Candidates

Analyzed all 16 net472-only .UnitTests projects in dotnet/roslyn. Excluded 9 with Visual Studio/WPF hard dependencies. 7 candidates remain.

Low Effort (easiest wins)

Project	Notes
CodeStyle/CSharp/Tests	Pure analyzer testing, no VS/WPF deps. Straightforward.
Features/ExternalAccess/OmniSharpTest	Minimal deps — OmniSharp.CSharp targets netstandard2.0. Very clean.

jaredpar

BlobBuilder Allocation Strategy Plan

Problem Statement

Roslyn's VBCSCompiler process suffers from significant byte[] allocations driven by System.Reflection.Metadata APIs, primarily through BlobBuilder. The goal is to enable a pooling strategy where Roslyn pre-allocates ~4MB of byte[] and PE file writing completes with zero (or near-zero) additional allocations.

BlobBuilder Architecture Deep Dive

What BlobBuilder Is

jaredpar

Intentional No-Action Comments in Roslyn

Comments across C# and VB files where developers explicitly indicated no action is taken.

---

C# Files

Compilers

jaredpar

Shutting down our build servers

Motivation

The .NET build contains a number of long lived server processes: msbuild nodes, razor and roslyn. A requirement of the .NET SDK is for customers to be able to reliably shut down all servers created during any build. This is important for shutting down a build operation and ensuring that no files remain locked on disk.

This challenging because there is no easy answer to discovering which processes are build servers:

• These are primarily .NET SDK process which means they all share the same process name: dotnet
• These processes do not have a strict parent / child relationship with build commands. Several, like roslyn, live past the msbuild nodes that created them.

jaredpar

public ref struct LineEnumerator(string filePath) : IDisposable
{
    private static SearchValues<char> NewLines = SearchValues.Create('\r', '\n');

    private StreamReader _reader = new StreamReader(filePath);
    private char[] _array = ArrayPool<char>.Shared.Rent(1024);

    // This represents the data read from the file that hasn't been processed yet. This will
    // be a subset of _array
    private Span<char> _buffer = Span<char>.Empty;

jaredpar

https://dev.azure.com/dnceng-public/public/_build/results?buildId=739416&view=ms.vss-test-web.build-test-results-tab&runId=18651876&resultId=178085&paneView=debug

Test_Windows_CoreClr_Release_Windows.10.Amd64.Open

https://helixre107v0xdeko0k025g8.blob.core.windows.net/dotnet-roslyn-refs-pull-74360-merge-f9bd5f237e064558a9/Microsoft.CodeAnalysis.CSharp.Emit.UnitTests_Microsoft.CodeAnalysis.CSharp.Emit2.UnitTests_3/1/console.3f9a596b.log?helixlogtype=result

Stack:

xUnit.net 00:00:24.77]     Microsoft.CodeAnalysis.CSharp.UnitTests.AttributeTests_CallerInfoAttributes.TestCallerFilePath1 [FAIL]

jaredpar

C:\Users\jaredpar\code\PublicBugs\CscAnal>REM passing Newtonsoft.Json.dll 13.0.0.0 works fine and results in the expected: 

C:\Users\jaredpar\code\PublicBugs\CscAnal>REM arning CS8785: Generator 'Generator' failed to generate source. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'ArgumentNullException' with message 'Value cannot be null. 

C:\Users\jaredpar\code\PublicBugs\CscAnal>REM Parameter name: source' 

C:\Users\jaredpar\code\PublicBugs\CscAnal>REM  

C:\Users\jaredpar\code\PublicBugs\CscAnal>REM Loaded modules: 

jaredpar

using System.Reflection.Metadata;
using System.Reflection.PortableExecutable;

Console.WriteLine(IsNullableEnabledAtBuild(@"C:\Users\jaredpar\temp\console\bin\Debug\net7.0\console.dll", out var reason));
Console.WriteLine(reason);

static bool IsNullableEnabledAtBuild(string assemblyFilePath, out string? reason)
{
    MetadataReaderProvider? pdbReaderProvider = null;
    try