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Slower OMX skim loading in 2.16 #90
Description
When testing Sharrow implementation for SANDAG ABM3 with ActivitySim 1.5.1, we found that runtime for mp_setup_skims was greatly increased when running with Sharrow 2.16. Downgrading to Sharrow 2.15 brought runtime back down, comparable to non-sharrow runs.
mp_setup_skims
Sharrow 2.16: 29.8 minutes (1789.4 seconds)
Sharrow 2.15: 7.4 minutes (446.4 seconds)
ActivitySim log files for both runs attached:
activitysim_sharrow_mp_test_2.log
activitysim_sharrow_mp_test_3.log
Activity
billyc commentedon Oct 29, 2026
@janzill -
per today's engr meeting, openmatrix v0.4.0 with h5py internals is now released on pypi.
janzill commentedon Oct 31, 2026
Nice, thanks Billy! @jpn-- this would be a good new baseline for comparisons in #87
janzill commentedon Nov 1, 2026
@aber-sandag local tests reproduced this issue for me when running with the SANDAG example model, although the factor was smaller, about 1.5x instead of the 4x you report. However, setting
BLOSC_NTHREADS=1made sharrow 2.16.2 load skims faster than v2.15. Can you add this to wherever you set your thread count restrictions and try sharrow 2.16 again and see if it resolves the issue, please?