The HSR Parallel Checker is a Visual Studio® extension that detects data races, deadlocks and other concurrency issues in C#.


  • Static: Finds issues that are hard to identify through tests.
  • Fast: Takes only a few seconds, even for large projects.
  • Precise: Detects real issues that can occur indeed at runtime.
  • Interactive: Highlights issues while coding in Visual Studio IDE.

August 2019: Version 1.1 Released!

The latest HSR Parallel Checker supports Visual Studio 2019 and C# 8. Error messages have been improved to provide more details about the error causes, including call chains. Due to user feedback, diagnostic information messages have been turned off by default.

July 2018: Publication Appeared!

The checker algorithm, design and implementation is described in an academic publication:

  • L. Bläser. Practical Detection of Concurrency Issues at Coding Time. International Symposium on Software Testing and Analysis (ISSTA) 2018, Amsterdam, The Netherlands, In ACM Digital Library, July 2018.

Notice: Microsoft, Visual Studio, and Visual Basic are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries.

All trademarks, trade names etc. are the property of their respective owners.

HSR, HSR Parallel Checker, and the contributors DO NOT have any affiliation with any mentioned trademark holders.