Strange GC issue on Julia 1.12-rc1

General Usage Performance
,
2

On v1.12.0-rc1 I get a precompilation error:

ERROR: LoadError: UndefVarError: `tmpM` not defined in `FLORIDyn`
Suggestion: check for spelling errors or missing imports.
Stacktrace:
  [1] runFLORIDyn(plt::Nothing, set::FLORIDyn.Settings, wf::FLORIDyn.WindFarm, wind::FLORIDyn.Wind, sim::FLORIDyn.Sim, con::FLORIDyn.Con, vis::FLORIDyn.Vis, floridyn::FLORIDyn.FloriDyn, floris::FLORIDyn.Floris, pff::Nothing; msr::FLORIDyn.MSR)
    @ FLORIDyn ~/FLORIDyn.jl/src/floridyn_cl/floridyn_cl.jl:1036
  [2] runFLORIDyn
    @ ~/FLORIDyn.jl/src/floridyn_cl/floridyn_cl.jl:1004 [inlined]
  [3] runFLORIDyn(plt::Nothing, set::FLORIDyn.Settings, wf::FLORIDyn.WindFarm, wind::FLORIDyn.Wind, sim::FLORIDyn.Sim, con::FLORIDyn.Con, vis::FLORIDyn.Vis, floridyn::FLORIDyn.FloriDyn, floris::FLORIDyn.Floris)
    @ FLORIDyn ~/FLORIDyn.jl/src/floridyn_cl/floridyn_cl.jl:1004
...

It’s probably this line:

a = @allocated tmpM, wf = setUpTmpWFAndRun(set, wf, floris, wind)

Something about the @allocated macro has changed, so a begin ... end is required:

a = @allocated begin tmpM, wf = setUpTmpWFAndRun(set, wf, floris, wind) end

I’ll enter an issue in github for it. (EDIT: The `@allocated` macro differs between v1.11 and v1.12.0-rc1 · Issue #59256 · JuliaLang/julia · GitHub)

Otherwise, the run I did on v1.11 indicates that the run is very allocation intensive. This is known to cause performance problems for parallel programs, and any minor change in the garbage collector will have a major impact.

EDIT: The begin ... end will not allow tmpM and wf to be set.