[pymvpa] Never-ending searchlight

Christopher J Markiewicz effigies at bu.edu
Thu Jan 29 21:17:39 UTC 2015

At commit: 573883e099a598c127fc5076123ebe3906f2be82

Running into a weird issue where under one (of 120) combination of
parameters, the searchlight hangs and never ends. On a 16 core machine,
16 cores will run for about 1.5-2 hours, and then one core will be at
100% until terminated (longest run was ~3 weeks, having forgotten about
it over break).

I post the searchlight sequence below for the sake of context, and in
the hope that this is where the problem is, but it should be noted that
the difference is entirely in which dataset is loaded. The dataset loads
without error and contains no NaNs. Foolishly, I haven't saved a copy of
the stack trace, but a SIGTERM will result in a numpy shape coercion
error. (Will rerun and send along the stack trace when I can.)

Given a fmri_dataset ds and a QueryEngine qe, we use the following

cn = ChainNode([NFoldPartitioner(),
                Balancer(attr='targets', count=2, limit='partitions',
                         apply_selection=True)], space='partitions')

svm = LinearCSVMC()
cvte = CrossValidation(svm, cn)
sl = Searchlight(cvte, qe, postproc=mean_sample())

errors = sl(ds)
nifti = map2nifti(dataset, 1 - errors.samples)


Thanks in advance for any help.

Christopher J Markiewicz
Ph.D. Candidate, Quantitative Neuroscience Laboratory
Boston University

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