dotnet/runtime

`NamedPipeServerStream` recieves empty string from client

Open

#112,912 opened on Feb 25, 2025

View on GitHub
 (1 comment) (1 reaction) (0 assignees)C# (17,886 stars) (5,445 forks)batch import
area-System.IOhelp wanted

Description

Description

When a named pipe client sends a string, System.IO.Pipes.NamedPipeServerStream in my application sometimes, usually the first request after application started running, gets it as a empty string "" from the StreamReader.

Reproduction Steps

Created a repository to reproduce the issue. Note that my client is written in Rust. https://github.com/U-C-S/NamedPipesWindows-IssueRepro

Expected behavior

Named Pipe Server should get the string from client as it is, on all occasions.

Actual behavior

Named Pipe Server gets an empty string occasionally from client, even when client certainly is sending a non-empty string, usually on first launch of the application the server is part of.

image

Regression?

No response

Known Workarounds

No response

Configuration

  • .NET SDK version: 8.0.404
  • OS and version: Windows 11 stable build 26100.3194
  • architecture: x64
  • Do you know whether it is specific to that configuration? - No

Other information

No response

Contributor guide

Tech stack
csharprust
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
understanding of Windows named pipesfamiliarity with .NET I/Obasic knowledge of Rust interop
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Investigate the race condition causing occasional empty string reads on the server. Start by examining the reproduction repo at https://github.com/U C S/NamedPipesWindows IssueRepro. Check the StreamReader usage on the server side, specifically the ReadToEnd or ReadLine calls, and ensure proper flushing and async handling. Compare with the Rust client's write pattern (e.g., size prefix, trailing newline). Look for any Windows specific named pipe quirks, such as message mode vs byte mode. Consider if the issue is related to pipe buffer initialization or timing between connection and reading. Check existing .NET runtime issues for similar named pipe bugs.