{"id":23792,"date":"2024-05-30T09:08:23","date_gmt":"2024-05-30T07:08:23","guid":{"rendered":"https:\/\/info.gwdg.de\/news\/?p=23792"},"modified":"2024-07-08T16:41:45","modified_gmt":"2024-07-08T14:41:45","slug":"openfoam-debugging","status":"publish","type":"post","link":"https:\/\/info.gwdg.de\/news\/openfoam-debugging\/","title":{"rendered":"OpenFOAM Debugging"},"content":{"rendered":"

Debugging is often an essential part of software development. In the scope of this tutorial, I will present a couple of tools with OpenFOAM as a practical example of a C++based scientific simulation code. After a brief reminder aboute the installation procedure of the OpenFOAM flavor foam-extend 4.1, the blog article introduces debugging with gdb and the IDEs Visual Studio Code and Qtcreator.<\/p>\n

The demo problem is based on the pitzDaily tutorial in foam-extend and uses the scalarTransportFoam solver which implements the equation:
\n\ud835\udeff<\/span>\ud835\udc47<\/span><\/span>\ud835\udeff<\/span>\ud835\udc61<\/span><\/span><\/span>+<\/span>\u2207<\/span>\u22c5<\/span>(<\/span>\ud835\udc62<\/span>\ud835\udc47<\/span>)<\/span><\/span>\u2212<\/span>\u2207<\/span>\u22c5<\/span>(<\/span>\u2207<\/span>\ud835\udc37<\/span>\ud835\udc47<\/span><\/span>\ud835\udc47<\/span>)<\/span><\/span>=<\/span>\ud835\udc46<\/span><\/span><\/span><\/span><\/span><\/p>\n

The geometry of the case is shown in Paraview below:
\n\"\"<\/a><\/p>\n

Requirements – OpenFOAM base installation Ubuntu 20.04 LTS<\/h2>\n

The tutorial assumes that you are running a system with Ubuntu 20.04 LTS installed. It is based on the installation instructions from the OpenFOAMwiki<\/a>. The required base packages can be then installed using the following commands:<\/p>\n

sudo apt-get<\/span> update<\/span> \r\nsudo apt-get<\/span> install git-core build-essential binutils-dev<\/span> cmake \r\n                     flex zlib1g-dev<\/span> libncurses5-dev<\/span> curl bison \\\r\n                     libxt-dev<\/span> rpm mercurial graphviz python \\ \r\n                     python-dev<\/span> gcc-7<\/span> g++-7<\/span> paraview gdb\r\n\r\n<\/code><\/pre>\n
mkdir<\/span> ~\/foam\r\ncd<\/span> ~\/foam\r\ngit clone http:\/\/git.code.sf<\/span>.net\/p<\/span>\/foam-extend<\/span>\/foam-extend<\/span>-4.1<\/span> foam-extend<\/span>-4.1\r\n<\/span>\r\n<\/code><\/pre>\n
For a successful building of foam-extend-4.1, we will use here GCC-7. In order to configure foam-extend to use it we need to add the following lines to etc\/prefs.sh in the OpenFOAM folder:<\/p>\n
export<\/span> WM_CC<\/span>='gcc-7'<\/span>\r\nexport<\/span> WM_CXX<\/span>='g++-7'\r\n\r\n<\/span>\r\n<\/code><\/pre>\n
We apply the changes by sourcing the OpenFOAM bashrc file by executing the following line in the terminal:<\/p>\n
source<\/span> etc\/bashrc\r\n<\/code><\/pre>\n
sed -i -e 's=rpmbuild --define=rpmbuild --define \\\r\n            \"_build_id_links none\" --define=' \\\r\n            ThirdParty\/tools\/makeThirdPartyFunctionsForRPM\r\nsed -i -e 's\/gcc\/\\$(WM_CC)\/' wmake\/rules\/linux64Gcc\/c\r\nsed -i -e 's\/g++\/\\$(WM_CXX)\/' wmake\/rules\/linux64Gcc\/c++\r\n\r\n<\/code><\/pre>\n
In order to use both the productive and debug versions easily, it is convienient to define correseponding aliases. In order to do so the two lines should be added to the .bashrc file in the home directory. This can be either done by copying and pasting the following two lines to the terminal window or by manually adding the text between the quotation marks with your favorite text editor.<\/p>\n
echo<\/span> \"alias fe41='source \\ \r\n            \\$HOME\/foam\/foam-extend-4.1\/etc\/bashrc'\"<\/span> >> ~\/.bashrc\r\necho<\/span> \"alias fe41_debug='source \\\r\n            \\$HOME\/foam\/foam-extend-4.1\/etc\/bashrc \\\r\n            WM_COMPILE_OPTION=Debug'\"<\/span> >> ~\/.bashrc\r\n\r\n<\/code><\/pre>\n
With this setup it is possible to compile both the optimized and the debug version using the following commands:<\/p>\n
cd ~\/foam\/<\/span>foam-extend-4.1<\/span>\r\nsource<\/span> ~\/foam\/<\/span>foam-extend-4.1<\/span>\/etc\/<\/span>bashrc\r\n.\/Allwmake.firstInstall\r\nWM_COMPILE_OPTION=Debug .\/Allwmake\r\n\r\n<\/code><\/pre>\n
The discussed IDEs QtCreator and Visual Studio Code are installed using
\nthe package management system using:<\/p>\n
sudo apt-get<\/span> install qtcreator\r\nsnap install code --classic\r\n<\/span>\r\n<\/code><\/pre>\n
The code needed for this tutorial can be found here<\/a>.<\/p>\n
Debugging Tools<\/h3>\n
Basic debugging can be accomplished by sending text messages to the terminal through the addition of \u201cInfo\u201d sections. This approach helps in understanding the execution flow of the code and pinpointing where it stops working.<\/p>\n
Info<< \"\\nStarting time loop\\n\"<\/span> << endl;\r\n\r\nwhile<\/span> (runTime.loop<\/span>())\r\n{\r\n    Info<< \"Time = \"<\/span> << runTime.timeName<\/span>() << nl << endl;\r\n      ...\r\n}\r\n<\/code><\/pre>\n
 <\/p>\n
However, there are some downsides to this method. It offers no control over the code during execution, requires modifying and recompiling the code, and necessitates cleaning up the code after successful debugging.<\/p>\n
Understanding Debug Switches in OpenFOAM<\/h3>\n
In OpenFOAM, debug switches offer a flexible way to manage debugging information without the need for recompilation, unlike traditional \u201cInfo\u201d statements. These switches can be turned on and off and are defined in the controlDict<\/code> for a specific case, allowing users to set different debug levels to control the verbosity of the output.<\/p>\n
Key Features of Debug Switches<\/h4>\n
The source code of foam-extend 4.1 is available as a git repository at Sourceforge.net<\/a> and can be cloned using the following commands:<\/p>\n