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Job arrays: Difference between revisions
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== Example: Data-parallel Python script == | == Example: Data-parallel Python script == <!--T:19--> | ||
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Suppose you have a Python script doing certain calculations with some parameters defined in a Python list or a NumPy array such as | Suppose you have a Python script doing certain calculations with some parameters defined in a Python list or a NumPy array such as | ||
{{File | {{File | ||
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import numpy as np | import numpy as np | ||
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def calculation(x, beta): | def calculation(x, beta): | ||
time.sleep(2) #simulate a long run | time.sleep(2) #simulate a long run | ||
return beta * np.linalg.norm(x**2) | return beta * np.linalg.norm(x**2) | ||
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if __name__ == "__main__": | if __name__ == "__main__": | ||
x = np.random.rand(100) | x = np.random.rand(100) | ||
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print(res) #show the results on screen | print(res) #show the results on screen | ||
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# Run with: python my_script.py | # Run with: python my_script.py | ||
}} | }} | ||
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The above task can be processed in a job array so that each value of the beta parameter can be treated in parallel. | The above task can be processed in a job array so that each value of the beta parameter can be treated in parallel. | ||
The idea is to pass the <code>$SLURM_ARRAY_TASK_ID</code> to the Python script and get the beta parameter based on its value. | The idea is to pass the <code>$SLURM_ARRAY_TASK_ID</code> to the Python script and get the beta parameter based on its value. | ||
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import sys | import sys | ||
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def calculation(x, beta): | def calculation(x, beta): | ||
time.sleep(2) #simulate a long run | time.sleep(2) #simulate a long run | ||
return beta * np.linalg.norm(x**2) | return beta * np.linalg.norm(x**2) | ||
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if __name__ == "__main__": | if __name__ == "__main__": | ||
x = np.random.rand(100) | x = np.random.rand(100) | ||
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print(res) #show the results on screen | print(res) #show the results on screen | ||
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# Run with: python my_script_parallel.py $SLURM_ARRAY_TASK_ID | # Run with: python my_script_parallel.py $SLURM_ARRAY_TASK_ID | ||
}} | }} | ||