Helgrind: Detecting Synchronisation Issues in Multithreaded Programs

Let's explore how Helgrind can be used to detect and debug multithreading issues with the help of a multithreaded C program.

- Subranshu Patel

Multithreading is a programming paradigm that allows concurrent execution of multiple threads within a single process, and is popular in modern software development for its ability to improve performance and responsiveness in applications. However, this comes with inherent thread synchronisation challenges like race conditions and deadlock. These can be very difficult to detect and debug due to the following reasons.

Non-determinism: Thread execution order and timing are unpredictable. These can vary between runs, even on the same hardware, making it difficult to reproduce bugs.

Heisenbug effect: Using a debugger to pause and examine threads can potentially change their execution order, making the issue disappear.

Overview of Helgrind

Helgrind is a tool within the Valgrind suite and is designed to assist developers in identifying thread synchronisation issues. It focuses specifically on detecting errors related to the use of POSIX pthread APIs. Helgrind can be used for C, C++ and Fortran programs, and analyses the behaviour of threads and thread APIs during program execution. It identifies potential issues related to thread synchronisation.

Helgrind can detect three categories of errors.

Incorrect use of POSIX pthread APIs: