Edit: Please see the #7 post directly if you’re interested. Thanks. The idea is: I at first create a Vector v = Vector{Matrix{Float64}}(undef, 100); Then I need to fill it with some concrete objects (here are matrices): for i = 1:100 v[i] = rand(9999,9999) end These operations will use muc…

According to my observation from the htop in zsh, the occupation at three instances are illustrated below const S = 256 const GRB_ENV = Gurobi.Env(); const m = Vector{JuMP.Model}(undef, S); function my_initialize(GRB_ENV) m = JuMP.direct_model(Gurobi.Optimizer(GRB_ENV)) JuMP.set_attribute(m…

The Gurobi.Env object is not thread-safe. I guess I need to update: [image] GitHub - jump-dev/Gurobi.jl: A Julia interface to the Gurobi Optimizer A Julia interface to the Gurobi Optimizer In addition, you must not simultaneously create multiple model…

[image] odow: Otherwise: this code should work. The behavior is now 858M → 4.69G → 4.65G, even if I’ve removed the GRB_ENV dependency (see the cyan arrow below). [image]

I even further removed the Gurobi dependency and work with JuMP.Model() now. The major memory is still unreclaimed (793M → 3.14G → 2.73G) [image] If I further enlarge S from 256 to 2560, then memory pattern now is 878M → 11.2G → 9.21G

Try running GC.gc() multiple times. And add a return nothing to the end of perfect_consts!. You must have a reference somewhere that is preventing the models from being garbage collected. Does it happen if you remove Threads.@spawn? I don’t think this is related to JuMP.

[image] odow: I don’t think this is related to JuMP. I agree. I find that the manual GC.gc() appears to be nondeterministic, via this self-contained general example: function f!(v) m = v[end] for i = eachindex(v) v[i] = m end end; # 662M here v = map(fetch, [Threads.@spa…

This might have changed in the last few versions since I learned this, but Julia doesn’t always release memory to the OS when it’s released within Julia, depending on memory pressure on the system and within Julia. You may try ccall(:malloc_trim, Int32, (Int32,), 0) to release held memory.

[image] odow: In addition, you must not simultaneously create multiple models using the same environment. I’ve discovered how to build independent models properly (probably). ▶ Code

Sometimes cannot reclaim memory by manual GC.gc()

General Usage

gbaraldi January 20, 2026, 5:40pm 9

FYI this isn’t Julia, this is just the allocator in libc (Julia will even call that function automatically for you depending on the condition)

How to manage memory when using JuMP+Gurobi?

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Sometimes cannot reclaim memory by manual GC.gc()

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