CheckpointFile usage #4450
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Hi! I am trying to create CheckpointFiles and then to restart the simulation from a previous CheckpointFile. I am following the documentation: https://www.firedrakeproject.org/checkpointing.html. 1checkpoint_minimal_example.zip python3 checkpoint_minimal_example.py _checkpoint_minimal_example --- Function Space Details (2D) --- 2I also tried with the mesh defined as: mesh = UnitSquareMesh(10, 10, name="Mesh"). Nothing different. 3Then I tried with the mixed space pressure-velocity function: 4without saving and loading the mesh which is indicated to be otional in the documentation (https://www.firedrakeproject.org/checkpointing.html.), I get the following error: (venv-firedrake) madalinaphys@madalinaenciu:~/Documents/STRASSE_LH2_Simulation/Thermosiphon_2D$ python3 checkpoint_minimal_example.py _checkpoint_minimal_example --- Function Space Details (2D) --- Could you guide me with what I am doing wrong? Thank you! |
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Replies: 1 comment 5 replies
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I managed to figure out while explaining it in the question :) |
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Good to hear. Can you describe briefly what you did to fix it? It would be helpful to others if they encounter the same issue and find this discussion. |
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Ideally I would like that the definitions of functions loaded from the CheckpointFile to be identical to the functions that I define using the example of case (a.). |
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I think that only saving the mesh is supposed to be optional. The documentation states:
I think that this isn't really possible. Our checkpointing assumes that you could be loading from a different number of processors than you wrote from and so we can't make any guarantees about the mesh partitioning and hence the DoF numbering and sizes of the local arrays. |
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Thank you! 👍 |
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Actually, if you use the same number of processes for loading, you will get a mesh of the exact same data structure (distribution + reordering) by default. However, the loaded mesh and the saved mesh are still different objects, so |
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Saving and loading the mesh seems to be necessary. I am not sure why in the documentation it is said to be optional (https://www.firedrakeproject.org/checkpointing.html.) Can somebody give a working example where you can later load functions from a CheckpointFile without a mesh? What is different in my case?
The other errors come from the fact that the definition of the functions using for example:
a. V_T = FunctionSpace(mesh, T_element)
V_T.name = "TemperatureSpace"
temp = Function(V_T, name="Temperature")
is completely different than:
b. with CheckpointFile(restart_file, 'r') as chk:
mesh = chk.load_mesh("Mesh")
temp = chk.load_function(mesh, name="Temperature"
seem to be different.
B…