Debugging with DDT Allinea Map

Objective

Background of this item: when the model does not run as expected, the calculations will need to be checked step by step. Debuggers such as IDB help to identify what are the values taken by some variables at some point, check that a subroutine of interest is actually called during the execution of the code (and how many times it happens),... This might be very useful when one would like to speed up the identification of the variable which is the first to take weird values (particularly after a significant modification of the code) and the snap of code which cause that trouble. An basic alternative to the use of debuggers is added WRITE statements to the code.

Boundary conditions for using a debugger

Of course, getting a functional version of the code after a modification of one of the routine of ORCHIDEE continues to require a few steps and the debugger we present only helps to speed up the second one :

1. Getting a version of the code which can be compiled. The first errors displayed by the compiler before crashing should be of some help to solve that issue.
2. Once the code including the modification can be compiled properly, it may often happen that some of the variables take aberrant values, even for runs in offline mode on one point. You are likely to be interested by this tutorial if you are used to proceed to tedious cycles of :
   • addition within the subroutine of interest of lines such as "PRINT *, 'MY_VAR='my_var
   • compilation of the code
   • screening of the standard output of the executed code
3. Check that the introduction of the new feature doesn't lead to weird behaviour for runs at the global scales and/or coupled with the GCM.

DDT Allinea Map on Curie

Authors: A. Jornet
Last revision: A. Jornet (2019/05/02)

DDT is a parallel debugger found in Curie Hpc. How to run an Orchidee Parallel simulation with XIOS in server mode?

1- Load ddt and run in interative mode

module load ddt 
ddt &

2- Select Run (ddt main window)

3- Properly setup the simulation The total number of processors will be the sum of Orchidee and XIOS.

4- Click "Play" to start the simulation

5- For more info

​Youtube DDT tutorial video