Performance of FunctionWrappersQuickFix

[rdeits]

I noticed when trying to build a large Parametron model that I was spending an unreasonable amount of time just constructing the initial model. From profiling, it looks like almost all of the time is spent inside the FunctionWrappersQuickFix.FunctionWrapper constructor.

I was curious to see if the quick fix might be slowing things down, and it does appear that what we're doing is dramatically slower than the normal FunctionWrapper. For example:

julia> using FunctionWrappers, Parametron, BenchmarkTools

julia> function f1(x)
         Parametron.FunctionWrappersQuickFix.FunctionWrapper{Int, Tuple{Int}}(y -> y + x)
       end
f1 (generic function with 1 method)

julia> function f2(x)
         FunctionWrappers.FunctionWrapper{Int, Tuple{Int}}(y -> y + x)
       end
f2 (generic function with 1 method)

julia> @btime f1($1)
  188.514 ns (2 allocations: 64 bytes)
Parametron.FunctionWrappersQuickFix.FunctionWrapper{Int64,Tuple{Int64}}(Ptr{Nothing} @0x00007f9498be3570, Ptr{Nothing} @0x00007f9493ed8010, Base.RefValue{getfield(Main, Symbol("##7#8")){Int64}}(getfield(Main, Symbol("##7#8")){Int64}(1)), getfield(Main, Symbol("##7#8")){Int64})

julia> @btime f2($1)
  9.602 ns (2 allocations: 64 bytes)
FunctionWrappers.FunctionWrapper{Int64,Tuple{Int64}}(Ptr{Nothing} @0x00007f9498beada0, Ptr{Nothing} @0x00007f9493ed8020, Base.RefValue{getfield(Main, Symbol("##9#10")){Int64}}(getfield(Main, Symbol("##9#10")){Int64}(1)), getfield(Main, Symbol("##9#10")){Int64})

julia> versioninfo()
Julia Version 1.1.0
Commit 80516ca202 (2019-01-21 21:24 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Xeon(R) CPU E3-1535M v6 @ 3.10GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, skylake)

so FunctionWrappers.FunctionWrapper is about 20x faster to construct for this example.

I'm not sure what exactly we can do about it, other than to keep making noise over at JuliaLang/julia#28669

[tkoolen]

I'm not sure what exactly we can do about it, other than to keep making noise over at JuliaLang/julia#28669

Thanks for doing so and reevaluating the current state of affairs.

[tkoolen]

Now we should remember that FunctionWrappers.FunctionWrapper is not actually functional on Julia 1, so the very thing that makes it fast could also be what makes it not work.

Also, for onlookers, it should be noted that FunctionWrappers are not created during solve!, only during problem setup stage.

[rdeits]

Well, it's not completely broken:

julia> using FunctionWrappers: FunctionWrapper

julia> f = FunctionWrapper{Int, Tuple{Int, Int}}((x, y) -> x + y)
FunctionWrapper{Int64,Tuple{Int64,Int64}}(Ptr{Nothing} @0x00007f10eb6e90c0, Ptr{Nothing} @0x00007f1104b086f0, Base.RefValue{getfield(Main, Symbol("##7#8"))}(getfield(Main, Symbol("##7#8"))()), getfield(Main, Symbol("##7#8")))

julia> f(1, 2)
3

it just still fails occasionally in a way I don't understand.