The source code and dockerfile for the GSW2024 AI Lab.
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Thread local memory example===========================
The GLPK library, when compiled with default options, uses a separate environmentfor each thread that is executed. So each thread is isolated. The only exeptionis error handling. An error in any of the library functions will not onlyterminate the active thread but the complete process.
This can be circumvented by defining an error handling routine withglp_error_hook(). This directory contains an example demonstrating running amultithreaded application with error handling.
The example code----------------
The program multiseed solves a MathProg model multiple times in separate parallelthreads. Each threads uses a different seed for the MathProg pseudo random numbergenerator.
The MathProg model clustering.mod generates 50 randomly distributed "towns". Outof the towns it selects 3 to be cluster centers and assign the other towns to theclusters such that the sum of the population weighted euclidian distances betweentowns and centers is minimized.
The solution is written to a Scalable Vector File which can be viewed with a webbrowser.
For demonstration purposes at the end of every third thread the error handlingroutine is triggered by calling glp_error(). This results in output like
18-00086 Model has been successfully processed 18-00087 Voluntarily throwing an error in multiseed.c at line 147 18-00088 Error detected in file multiseed.c at line 146 18-00089 Error caught
Terminal output is preceeded by numbers indicating the thread index and theoutput line. You can pipe it through sort to get a better overiew, e.g.
multiseed clustering.mod 20 | sort
Building and running the example code-------------------------------------
On Linux multiseed can be compiled with gcc by calling
make
The code can be executed with
make check
For compiling the example on 64bit Windows with Microsoft Visual Studio C++ run
Build_Multiseed.bat
You may have to adust the variable HOME in the batch file depending on theinstallation path of Visual Studio.
You can run multiseed with
multiseed <filename> <count>
Where filename is the path to the model file and count is the number of parallelthreads.
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