Delay Differential Equations Networks with different delay per edge

Here I reported that for some reason when using Julia 1.8.0-beta3 and loading DifferentialEquations.jl, the reproducer of the Base inference issue gives different results (and seems to work well in that case). However, under those conditions the poor performance of the DDE with heterogeneous delays posted here remains the same. So maybe the suggested reproducer is not good for that Base inference issue but it is also possible that the DDE performance problem has another cause.

@ChrisRackauckas, could you run the code that led you to the conclusion that the cause of the DDE issue is the Base inference issue again but this time on Julia 1.8.0-beta3 while loading DifferentialEquations.jl, please?

Dear @ChrisRackauckas, the delayed Kuramoto code is still taking a lot more time using the suggested code than with the Python alternative Jitcdde. Do you know if there is any fix coming soon by any chance?

Can you try the v1.8-beta3 and nightly to see if the allocations from the interpolations are gone?

Try the example from Significant allocations with Callbacks (Tsit5) . It’s the same problem as callbacks. That interpolation inference bug makes it so every use of the interpolations has allocations. In theory it was fixed by

it would be good to get a confirmation of that, since it should be on v1.8. If that’s fixed, then the rest should be much simpler.


Thanks for your reply!

TL;DR: Both for the Callbacks example and for the delayed Kuramoto, the allocations are significantly reduced but the computation times remain similar. For the delayed Kuramoto case, unfortunately the Python Jitcdde implementation is still at least 3 orders of magnitude more performant.

You can find the details bellow:

Example from Significant allocations with Callbacks (Tsit5)


[1dea7af3] OrdinaryDiffEq v6.10.0
[6e4b80f9] BenchmarkTools v1.3.1

Running on Julia versions 1.8.0-beta3 and1.9.0-DEV.439 (current nightly)

@btime solve(prob,Tsit5()) # no callback


@btime solve(prob,Tsit5(), callback=cellFate) # with callback

I get

| n             | Julia version | time       | allocations |
| no callback   | 1.8.0-beta3   | 661.347 μs | 997.27 KiB  |
|               | 1.9.0-DEV.439 | 673.936 μs | 997.27 KiB  |
| with callback | 1.8.0-beta3   | 2.288 ms   | 1021.34 KiB |
|               | 1.9.0-DEV.439 | 2.292 ms   | 1021.34 KiB |

So there is no difference in performance nor in allocations between these Julia versions. Compared to the values reported in the original post (before the fix), there is a big improvement in terms of allocations but the performance ratio (time with call back / time without callback) remains similar.

Delayed Kuramoto


[bcd4f6db] DelayDiffEq v5.35.1
[31c24e10] Distributions v0.25.58
[1dea7af3] OrdinaryDiffEq v6.10.0
[6e4b80f9] BenchmarkTools v1.3.1

the following code (a wrap of all your suggestions from the previous replies)

using DelayDiffEq
using Distributions
using Random
using BenchmarkTools

function f!(dθ, θ, h::H, p, t) where H
    ω, A = p
    n = length(θ)
    lags = reshape(lag, n,n)
    @inbounds for j in 1:n
        coupling = 0.0
        @inbounds for i in 1:n
            coupling += A[i,j]*sin(h(p, t-lags[i,j]; idxs=i) - θ[j])
        dθ[j] = ω[j] + coupling

n = 10
ω = rand(n)
A = rand(n,n)
const lag = rand(n*n)
θ₀ = rand(Uniform(0, 2π), n)
p = (ω, A)
const past = rand(Uniform(0, 2π), n)
h(p, t; idxs=nothing) = typeof(idxs) <: Number ? past[idxs] : past

prob = DDEProblem(f!, θ₀, h, (0.0, 1.0), p, constant_lags=lag)
@btime solve(prob, MethodOfSteps(BS3()), saveat=0.01, reltol=0.0, abstol=1e-5)

depending on the number of oscillators n, gives the follwing results:

@btime solve(prob, MethodOfSteps(BS3()), saveat=0.01, reltol=0.0, abstol=1e-5)
| n  | Julia version | time      | allocations |
| 10 | 1.8.0-beta3   | 10.754 s  | 213.43 MiB  |
|    | 1.9.0-DEV.439 | 10.063 s  | 213.43 MiB  |
| 20 | 1.8.0-beta3   | 112.689 s | 1.74 GiB    |
|    | 1.9.0-DEV.439 | 119.260 s | 1.49 GiB    |

For the case of n = 10, those are half the allocations that you reported above but with not much difference in time.

On the other hand, when using n = 20 oscillators, the results from both Julia versions (which in this case are slightly different) are similar to those I posted above (before the fix):

@time solve(prob, MethodOfSteps(BS3()), saveat=0.01, reltol=0, abstol=1e-5)
119.585544 seconds (11.80 M allocations: 1.706 GiB, 3.26% gc time)

When solving with n = 20, the warning of Interrupted. Larger maxiters is needed. was raised. And I realized that the solver that I was using (BS3, matching the Jitcdde implementation) is a non-stiff solver and probably many Kuramotos with very different frequencies is a stiff system. When using the recommended TRBDF2 solver for stiff ODEs, these are the results:

@btime solve(prob, MethodOfSteps(TRBDF2()), saveat=0.01, reltol=0.0, abstol=1e-5)
| n  | Julia version | min time   | allocations |
| 10 | 1.8.0-beta3   | 993.642 ms | 52.72 MiB   |
|    | 1.9.0-DEV.439 | 1.104 s    | 52.72 MiB   |
| 20 | 1.8.0-beta3   | 193.267 s  | 1.62 GiB    |
|    | 1.9.0-DEV.439 | 1566.749 s | 1.62 GiB    |

So you can see that TRBDF2 greatly improved the time and allocations in the case of the n = 10 but for n = 20 the performance got much worse (with a greater difference in the nightly version). The maxiter warning was still raised for n = 20 when using TRBDF2, so I’m still looking for the cause of that. If you have any insight, I’ll be very grateful.

Unfortunately, the Python implementation with Jitcdde still seems more performant that the Julia implementation. For n = 10 we don’t have the maxiter warning and the best I could get with TRBDF2 was ~ 1 s, while with the Python Jitcdde (even with the default Bogacki–Shampine pair solver) it takes ~ 0.005 s for the n = 10 case, and ~ 0.007 s for n = 20.

By the way, what is the right way to include the jacobian for a DDE? Is it possible to calculate the symbolic jac automatically? I was trying with modelingtoolkitize without success. This won’t solve the probem causeing the maxiter warining but at least I wanted to see how much I could improve the performance for the n = 10 case.

Can you share some flamegraphs with GitHub - tkluck/StatProfilerHTML.jl: Show Julia profiling data in an explorable HTML page ?

For some reason I’m getting errors when trying to use StatProfilerHTML.jl:

ERROR: KeyError: key 0x0000000000000003 not found
[1] getindex
@ ./dict.jl:498 [inlined]
[2] StatProfilerHTML.Reports.Report(data::Vector{UInt64}, litrace::Dict{UInt64, Vector{Base.StackTraces.StackFrame}}, from_c::Bool)
@ StatProfilerHTML.Reports ~/.julia/packages/StatProfilerHTML/FRimo/src/Reports.jl:106
[3] statprofilehtml(data::Vector{UInt64}, litrace::Dict{UInt64, Vector{Base.StackTraces.StackFrame}}; from_c::Bool, path::String)
@ StatProfilerHTML ~/.julia/packages/StatProfilerHTML/FRimo/src/StatProfilerHTML.jl:23
[4] statprofilehtml (repeats 3 times)
@ ~/.julia/packages/StatProfilerHTML/FRimo/src/StatProfilerHTML.jl:17 [inlined]
[5] top-level scope
@ ~/Documents/checking_Kuramoto_fix/checking_if_fixed.jl:94

Maybe it’s some compatibility issue with Julia 1.8 and nightly. Nevertheless, I created some flamegraphs with ProfileSVG.jl, which you can find here. If you download those svg files and open them with Chrome or some other browser you can get some interactivity.

They are all quite similar. Most of the time appears to be spent in taks_done_hook from task.jl but it seems that it was a known bug from profiling when using more than one thread. It was supposed to be fixed here but maybe it wasn’t. I’ll repeat the profiling later with a single thread.

1 Like

Here you have the profiling done right, with 1 thread.

So yeah if the number of steps is similar (is it?), then it all seems to be interpolation cost. So you’re sure the number of steps is the same? To me it sounds like you found an error estimate issue somewhere.