MaskBins is very slow on POWGEN

[Peter Peterson]

While trying out some things with SNSPowderReduction I discovered that when processing histogram nexus files (PG3_4565_histo.nxs) which have an excessive time-of-flight range which needs to be trimmed down it takes much longer than it should (2.7 hours, forced to be single threaded). I believe that it could be sped up by creating a second version of MatrixWorkspace::maskBin which takes a range of bin indices so it does the index checks only once per range of time bins that are being masked.

[Russell Taylor]

Shouldn't you be using CropWorkspace (might need to make event-aware) here? Or some other kind of event filtering? MaskBins was really conceived for cutting out narrow ranges somewhere in the center of the time range - e.g. a prompt pulse.

[Nick Draper]

Bulk move of tickets to iteration 31 at the iteration 30 code freeze

[Janik Zikovsky]

My guess is that the workspace went managed, if the # of tof bins was large. There isn't much to do to speed up all that disk access. An option would be to crop the workspace when loading, to avoid having to go managed in the first place.

[Nick Draper]

agreed

[Stuart Campbell]

This ticket has been transferred to github issue ​4412