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Know Your Bugs: Weapons for Efficient Debugging

  Copyright (c) 2013-2018 X. Besseron, UL HPC Team <>

The objective of this tutorial is to review the main tools that can be used to debug your [parallel] programs.

Hands/On 0 - Pre-requisites

Reserve 1 core (for 3h) over the UL HPC platform

  $> ssh gaia-cluster    # OR chaos-cluster
  $> oarsub -I -l core=1,walltime="03:00:00"

Hands/On 1 - GDB Tutorial

Tutorial from A GDB Tutorial with Examples

You'll need to load the latest GDB module:

  $> module spider gdb
  $> module load  debugger/GDB

Hands/On 2 - Valgrind Tutorial

Tutorial from Using Valgrind to Find Memory Leaks and Invalid Memory Use

You'll also need to load the appropriate module

  $> module spider valgrind
  $> module load debugger/Valgrind

Hands/On 3 - Bug Hunting

A list of programs demonstrating the different kind of bus are available in the exercises directory. Try the different debugging tools on every example to see how they behave and find the bugs.

Run the following command to download all the exercises:

$> git clone ulhpc-tutorials
$> cd ulhpc-tutorials/advanced/Debug/exercises/


  • You can compile each program manually using gcc or icc (the latest coming from the toolchains/ictce module). You are encouraged to try both to see how differently they behave. Example: gcc program.c -o program. Add any additional parameter you might need.
  • Some program required additional options to be compiled. They are indicated in comment at the beginning of each source file.