Cache the detector layout file in MetisLMSSpectralTraceList to avoid reading the file N*28 times for every OpticalTrain usage - #987
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MetisLMSSpectralTrace.fov_grid re-read and re-parsed the detector layout file from disk on every call. During construction of an LMS trace list it is called several times for each of the 28 slices (once per trace at construction, again through update_meta), so the same small file was read dozens of times. Wrap the read in a small lru_cache'd module function. Adds a test that the file is read only once for repeated calls.
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astronomyk
changed the title
MetisLMSSpectralTraceList to avoid reading the file N*28 times for every OpticalTrain usage
astronomyk
marked this pull request as ready for review
August 24, 2026 14:10
teutoburg
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Aug 24, 2026
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This shouldn't hurt I guess. Now stop playing with the toaster and go back to being a manager 😜
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TL;DR - tiny efficiency speed up to avoid excessive disk reads of the DetectorLayout file
@teutoburg requesting your review for this one as it's more about ScopeSim mehcanics, rather than METIS mechanics
What
MetisLMSSpectralTrace.fov_gridneeds the detector limits and read + parsed the layout file (!DET.layout.file_name) from disk on every call. Building an LMS trace list calls it several times for each of the 28 slices (trace construction,update_meta, volume setup), so the same small file was read dozens of times perOpticalTrain— more duringobserve().The read is wrapped in a small
lru_cache'd module function (maxsize=8, keyed on the filename), so each layout file is read once per session.Testing
TestDetectorLayoutCache::test_layout_file_is_read_only_oncecounts the actualascii.readcalls for repeated lookups.