Project Meeting 2023.03.16

Agenda

2 zone memory profiling

Notes

• Presentation: ActivitySim Memory Profiling Task – Progress Update 3-16-2023.pptx

• Models: placeholder_sandag and placeholder_psrc (only two 2-zone examples currently available)

  • SANDAG model doesn’t include the new features presented last week
  • SEMCOG 2-zone model is a PR but hasn’t been merged yet. RSG to pull it in and mark as ready.
  • 1-zone profiling included mtc, mwcog, arc

• SANDAG test: same peak memory despite tests with different sample sizes

  • Mandatory tour scheduling is not the memory peak
  • Accessibility calculation is same size regardless of sample size.
  • Memory peak because of all the MAZ OD pairs

• PSRC test: not able to run successfully with single processor

  • Need to change hardware or add chunking for accessibilities if we want to continue testing with this PSRC example
  • Instead of using this example, could use SEMCOG’s 2-zone example, once it's pulled in
  • Could chose number of processors by step (use multiprocessing for accessibilities)

• Potential future improvements (but haven’t tested these possibilities, just exploring ideas at this point)

  • Don’t do MAZ-MAZ costs because the skims are TAZ-based (what’s being done behind the scenes anyway)
    • Note size term is MAZ-MAZ
  • Adapt sampling process from disaggregate accessibilities RSG implemented in Phase 7, to avoid the full enumeration of MAZ-MAZ accessibilities.
    • Need to confirm where the accessibilities are being used and whether the disaggregate accessibilities would work for that particular model.
    • Depends on the costs that go into the accessibility utility function.
    • Needs to be carefully thought out, but tools and methods seem to be there if someone wanted to go this route for their model.

• Regarding memory allocation, how would you characterize ActivitySim's garbage collection behavior? Do we have anything that survive multiple garbage collection cycles?

  • Could be why there’s a zig-zag of memory profile or related to memory leak issue. WSP will be ooking into this is in a future task.

• Accessibility calcs and data types

  • Not many columns, mostly skims
  • Float 64 for skims
  • Accessibility terms are float 64 (10 different ones – auto/transit/non-motorized for peak/offpeak)

• Next steps

  • Next Thursday to present more on 2-zone memory profiling
  • Decide whether to sub SEMCOG for PSRC or change settings to be able to run PSRC