Hello,

I want to use BenchmarkTools to compare different model builds using JuMP for linear programming. Doing this for bigger linear problems took longer than I imagined. When looking at the results of ` @benchmark`

I noticed that the time to run the code I want to benchmark did just account for a small part of the time the whole benchmarking process took.

Here is the code I used. The function ` bench_array()`

is what I want to benchmark and the function ` benchmark_process_A()`

guides the benchmarking process.

```
module b_Array
export benchmark_process_A
using JuMP, CPLEX, BenchmarkTools, JLD, Dates
BenchmarkTools.DEFAULT_PARAMETERS.seconds = 600
BenchmarkTools.DEFAULT_PARAMETERS.samples = 5
function bench_array(A::Array{Float64,2},b::Array{Float64,1},n::Int64)
model = Model()
set_optimizer(model,CPLEX.Optimizer)
set_silent(model)
@variable(model, 0 <= x[1:n] <= 1)
@constraint(model, con[i = 1:n], sum(A[i, j] * x[j] for j = 1:n) <= b[i])
@objective(model, Max, sum(x))
return model
end
function benchmark_process_A()
n = 10000
A = rand(n,n)
b = rand(n)
println("Benchmarking Array started")
println(Dates.format(now(), "HH:MM:SS"))
benchmark = @benchmark bench_array($A,$b,$n)
println("Benchmarking Array finished")
println(Dates.format(now(), "HH:MM:SS"))
return benchmark
end
end
```

When I used ` benchmark_process_A()`

in the REPL I got the following results:

```
julia> include("b_Array.jl")
Main.b_Array
julia> using .b_Array
julia> benchmark = benchmark_process_A()
Benchmarking Array started
13:36:49
Benchmarking Array finished
14:04:24
BenchmarkTools.Trial:
memory estimate: 11.15 GiB
allocs estimate: 600881
--------------
minimum time: 64.891 s (7.13% GC)
median time: 94.437 s (17.59% GC)
mean time: 94.904 s (16.09% GC)
maximum time: 136.016 s (17.68% GC)
--------------
samples: 5
evals/sample: 1
```

I also looked at the times for each sample and got that in total the evaluation of all samples has taken `7.909 m`

. While the manual time measurenment 13:36:49 - 14:04:24 gives around ` 27.360 m`

.

Now I wonder what is happening in the remaining 20 minutes. Are there any problems with the way I wrote the code? I tried to encapsulate everything in functions and used interpolation when using `@benchmark`

. For any help I would be very thankful.