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This script lives in in /reg/g/psdm/tutorials/examplePythonexamplePython3/mpiReduce.py and demonstrates how to add arrays distributed across cores (e.g. area detector images) in a parallel MPI job.
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#run this with: mpirun -n 2 python mpiReduce.py from psana import * import numpy as np ds = DataSource('exp=xpptut15:run=54:smd') det = Detector('cspad') from mpi4py import MPI comm = MPI.COMM_WORLD rank = comm.Get_rank() size = comm.Get_size() img = None for nevent,evt in enumerate(ds.events()): if nevent%size!=rank: continue # different ranks look at different events if img is None: img = det.image(evt).astype(np.double) else: print (f'*{rank}',rank) img += det.image(evt) if nevent>=6: break imgsum = np.empty_like(img) comm.Reduce(img,imgsum) # sum the image across all ranks print ('Rank',: {rank},' sum:', {img.sum()}') if rank==0: print 'Total sum:',imgsum.sum() MPI.Finalize() |
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