# An undefined variable error during parallel computing
**URL:** https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482
**Category:** General Usage
**Tags:** parallel
**Created:** [June 7, 2021, 12:31am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482 "2021-06-07T00:31:05Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@marouane](https://discourse.julialang.org/u/marouane)
#### Post date: [June 7, 2021, 12:31am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/1 "2021-06-07T00:31:05Z")
an unexpected error happened while trying to use `Distributed` for the parallel computing of a module, my apologies if this questions is going to be a little bit long:
i already set up the cores and everything for distributed the module is like this:
```julia
module Quantum
using SymPy
using JuMP
using GLPK
using IterTools
using LLLplus
using GSL
using Distributions
using LinearAlgebra
using SmithNormalForm
export
qrelay_op,
op_mat,
scan_maker,
nonneg,
QRelaySampler
include("utility.jl")
include("operators.jl")
include("scan.jl")
include("distributions.jl")
struct QRelaySampler
prob::Function #return the probablility
psetproposal::Function #return next combination of sample
#input parameters:
#mat: the matrix p_ij in the note (10)
#coef: the coefficient c in the note (10)
#omega: the coefficient A in the note (10)
#pdet0: the probability of detection for each detector
function QRelaySampler(mat::Array{T, 2}, coef, omega, pdet0) where T <: Int
F=smith(mat)
U=F.S
V=F.T
S=diagm(F)
#the SmithNormalForm returns P=USV. Inverse the matrices so Ui/Vi is the same as U/V in the note (18)
Ui = inv(U)
Vi = inv(V)
s = diag(S)
r = count(!iszero, s)
s0 = s[1:r]
@assert s0 == ones(r)
ui1 = Ui[1:r, :]
ui2 = Ui[r+1:end, :]
vi1 = Vi[:, 1:r]
vi2 = Vi[:, r+1:end]
vi2 = lll(vi2)[1] #Lenstra–Lenstra–Lovász lattice basis reduction
T0 = vi1*ui1
ui2oc = orthocomp(ui2) #orhogonal complement
setc, scan = scan_maker(vi2) #make the scanner for the algorithm1 in the note
#compute the probability for an ideal system
#na: the photon numbers in a output mode
function prob(na)
@assert count(!iszero, ui2*na) == 0
b = T0*na
setc(-b)
total = 0.0
for x in Channel(scan)
nab = vi2*x + b #the photon numbers for each item in the sum in the note (10)
total += prod([c.^complex(n)/factorial(n) for (c, n) in zip(coef, nab)])
end
return abs2(total*omega)
end
#compute the probability of detection
#q: the number of photons detectors report
#na: the number of photons arrived at detector
#mask: if there is no detector in this channel, mask=0
function prob(q, na, mask)
q0 = round.(Int, q.>0)
m0 = round.(Int, mask)
return prod((q0 + (ones(length(q0))-2q0).*pdet0(na)).^m0)
end
psetproposal(x::Vector) = Quantum.OrthoNNDist(x, ui2oc)
new(prob, psetproposal)
end
end
end
```
then i include it on all the cores
`@everywhere include("Quantum.jl")`
`@everywhere using .Quantum`
then i have a metropolis-hastings algorithm that is written manually and works fine in case of serial computing:
```julia
@everywhere function relay_basis(alpha,delta,name::String,n) #n is the number of sources for 1 relay we have 2 sources
chi = fill(sqrt(0.06), n) # the parameter chi
phi = im*tanh.(chi)
omega = 1.0 / prod(cosh.(chi))^2
syms, op = qrelay_op(n, phi, alpha, delta)
op_a, op_ab, mat, coef = op_mat(op)
op_q2 = [syms.apH[1], syms.apV[1], syms.bpH[end], syms.bpV[end]]
op_q1 = [syms.apH[2:end]..., syms.apV[2:end]..., syms.bpH[1:end-1]..., syms.bpV[1:end-1]...]
mask_q1 = [op in op_q1 for op in op_a];
mask_q2 = [op in op_q2 for op in op_a];
qq = [x in syms.apH || x in syms.bpV ? 1 : 0 for x in op_a]
pdet0 = pdet_maker(0.04, 1e-5)
qrs = QRelaySampler(mat, coef, omega, pdet0)
targetcache=Dict{Vector{Int}, Float64}()
target(x::Vector)= log(qrs.prob(qq, x, mask_q1) * qrs.prob(x)) #the target function of MCMC
Iteration=10_000
burnin=1000
samples=Iteration+burnin
step=25
save_iter=burnin:step:samples
dist= qrs.psetproposal #the proposal distribution
selected=[]
Q = []
current_x = zeros(length(qq))
@time @distributed (+) for i= 2:samples #from this line the MCMC algorithm starts
proposed_x= rand(dist(current_x))
prop_proposed= pdf(dist(current_x), proposed_x)
prop_current= pdf(dist(proposed_x), current_x)
C=prop_current/ prop_proposed
A= min(1,C * exp(target(proposed_x) - target( current_x)))
if rand() < A
if i in save_iter
push!(selected, proposed_x)
push!(Q, qrs.prob(qq, proposed_x, mask_q2))
end
current_x = proposed_x
end
end
return selected, Q
end
```
and then i call this function inside a loop
```julia
@distributed (+) for i = 0:12
beta = i*pi/12
name = string(i)
@everywhere selected, Q = @everywhere relay_basis(pi/4, beta, name,2)
println("beta:", beta)
push!(prob,Q)
df=DataFrame(selected=selected)
end
```
i run it but i get this error:
```julia
On worker 2:
UndefVarError: beta not defined
top-level scope at none:1
eval at ./boot.jl:347
#103 at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:290
run_work_thunk at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:79
run_work_thunk at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:88
#96 at ./task.jl:356
Stacktrace:
[1] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:394
[2] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
[3] remotecall_fetch(::Function, ::Int64, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
[4] remotecall_fetch at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[5] (::Distributed.var"#157#158"{typeof(+),var"#14#15",UnitRange{Int64},Array{UnitRange{Int64},1},Int64,Int64})() at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:269
Stacktrace:
[1] wait at ./task.jl:267 [inlined]
[2] fetch at ./task.jl:282 [inlined]
[3] iterate at ./generator.jl:47 [inlined]
[4] collect(::Base.Generator{Array{Task,1},typeof(fetch)}) at ./array.jl:686
[5] preduce(::Function, ::Function, ::UnitRange{Int64}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:273
[6] top-level scope at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:284
[7] include_string(::Function, ::Module, ::String, ::String) at ./loading.jl:1091
```
like i said this code works fine without parallel computing but i want to enhance the performance and get better results.
I’d appreciate any help with this and if there is any question about the code you can ask it, in fact the entire module can be found on this link:
`https://github.com/marouanehanhasse/Quantum_Relay`
---
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [June 7, 2021, 1:15am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/2 "2021-06-07T01:15:07Z")
> [@marouane](#):
>
> ```julia
> @everywhere selected, Q = @everywhere relay_basis(pi/4, beta, name,2)
>
> ```
I think the error is a consequence of the `@everywhere` on this line, and I don’t see why you need. Does removing both `@everywhere` on this line solve your problem?
---
### Author:  [@marouane](https://discourse.julialang.org/u/marouane)
#### Post date: [June 7, 2021, 1:57am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/3 "2021-06-07T01:57:58Z")
now i get a `Fatal Error` it is quite long, i’m totally shocked:
```julia
Error: Fatal error on process 3
│ exception =
│ MethodError: no method matching write(::Sockets.TCPSocket, ::Cstring)
│ Closest candidates are:
│ write(::IO, ::Any) at io.jl:611
│ write(::IO, ::Any, !Matched::Any...) at io.jl:612
│ write(::IO, !Matched::Complex) at complex.jl:220
│ ...
│ Stacktrace:
│ [1] write(::Sockets.TCPSocket, ::Cstring) at ./io.jl:611
│ [2] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:638
│ [3] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [4] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [5] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [6] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [7] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [8] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [9] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [10] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [11] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [12] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [13] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [14] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [15] serialize at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627 [inlined]
│ [16] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Array{JuMP.ConstraintRef{JuMP.Model,MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64},MathOptInterface.GreaterThan{Float64}},JuMP.ScalarShape},1}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:272
│ [17] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [18] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [19] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [20] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [21] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [22] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [23] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [24] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [25] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [26] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [27] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Task) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:111
│ [28] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [29] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [30] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::CapturedException) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:212
│ [31] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [32] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [33] serialize_msg(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Distributed.ResultMsg) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:90
│ [34] #invokelatest#1 at ./essentials.jl:710 [inlined]
│ [35] invokelatest at ./essentials.jl:709 [inlined]
│ [36] send_msg_(::Distributed.Worker, ::Distributed.MsgHeader, ::Distributed.ResultMsg, ::Bool) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:186
│ [37] send_msg_now at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:130 [inlined]
│ [38] send_msg_now(::Sockets.TCPSocket, ::Distributed.MsgHeader, ::Distributed.ResultMsg) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:125
│ [39] deliver_result(::Sockets.TCPSocket, ::Symbol, ::Distributed.RRID, ::RemoteException) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:111
│ [40] macro expansion at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:302 [inlined]
│ [41] (::Distributed.var"#105#107"{Distributed.CallMsg{:call_fetch},Distributed.MsgHeader,Sockets.TCPSocket})() at ./task.jl:356
└ @ Distributed /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:115
Worker 3 terminated.
┌ Error: Fatal error on process 2
│ exception =
│ MethodError: no method matching write(::Sockets.TCPSocket, ::Cstring)
│ Closest candidates are:
│ write(::IO, ::Any) at io.jl:611
│ write(::IO, ::Any, !Matched::Any...) at io.jl:612
│ write(::IO, !Matched::Complex) at complex.jl:220
│ ...
│ Stacktrace:
│ [1] write(::Sockets.TCPSocket, ::Cstring) at ./io.jl:611
│ [2] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:638
│ [3] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [4] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [5] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [6] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [7] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [8] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [9] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [10] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [11] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [12] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [13] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [14] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [15] serialize at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627 [inlined]
│ [16] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Array{JuMP.ConstraintRef{JuMP.Model,MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64},MathOptInterface.GreaterThan{Float64}},JuMP.ScalarShape},1}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:272
│ [17] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [18] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [19] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [20] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [21] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [22] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [23] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [24] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [25] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [26] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [27] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Task) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:111
│ [28] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [29] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [30] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::CapturedException) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:212
│ [31] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [32] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [33] serialize_msg(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Distributed.ResultMsg) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:90
│ [34] #invokelatest#1 at ./essentials.jl:710 [inlined]
│ [35] invokelatest at ./essentials.jl:709 [inlined]
│ [36] send_msg_(::Distributed.Worker, ::Distributed.MsgHeader, ::Distributed.ResultMsg, ::Bool) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:186
│ [37] send_msg_now at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:130 [inlined]
│ [38] send_msg_now(::Sockets.TCPSocket, ::Distributed.MsgHeader, ::Distributed.ResultMsg) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:125
│ [39] deliver_result(::Sockets.TCPSocket, ::Symbol, ::Distributed.RRID, ::RemoteException) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:111
│ [40] macro expansion at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:302 [inlined]
│ [41] (::Distributed.var"#105#107"{Distributed.CallMsg{:call_fetch},Distributed.MsgHeader,Sockets.TCPSocket})() at ./task.jl:356
└ @ Distributed /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:115
Worker 2 terminated.
TaskFailedException:
ProcessExitedException(2)
Stacktrace:
[1] try_yieldto(::typeof(Base.ensure_rescheduled)) at ./task.jl:656
[2] wait at ./task.jl:713 [inlined]
[3] wait(::Base.GenericCondition{ReentrantLock}) at ./condition.jl:106
[4] take_buffered(::Channel{Any}) at ./channels.jl:387
[5] take!(::Channel{Any}) at ./channels.jl:381
[6] take!(::Distributed.RemoteValue) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:599
[7] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:390
[8] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
[9] remotecall_fetch(::Function, ::Int64, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
[10] remotecall_fetch at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[11] (::Distributed.var"#157#158"{typeof(+),var"#16#17",UnitRange{Int64},Array{UnitRange{Int64},1},Int64,Int64})() at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:269
Stacktrace:
[1] wait at ./task.jl:267 [inlined]
[2] fetch at ./task.jl:282 [inlined]
[3] iterate at ./generator.jl:47 [inlined]
[4] collect(::Base.Generator{Array{Task,1},typeof(fetch)}) at ./array.jl:686
[5] preduce(::Function, ::Function, ::UnitRange{Int64}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:273
[6] top-level scope at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:284
[7] include_string(::Function, ::Module, ::String, ::String) at ./loading.jl:1091
┌ Error: Fatal error on process 5
│ exception =
│ MethodError: no method matching write(::Sockets.TCPSocket, ::Cstring)
│ Closest candidates are:
│ write(::IO, ::Any) at io.jl:611
│ write(::IO, ::Any, !Matched::Any...) at io.jl:612
│ write(::IO, !Matched::Complex) at complex.jl:220
│ ...
│ Stacktrace:
│ [1] write(::Sockets.TCPSocket, ::Cstring) at ./io.jl:611
│ [2] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:638
│ [3] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [4] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [5] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [6] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [7] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [8] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [9] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [10] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [11] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [12] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [13] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [14] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [15] serialize at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627 [inlined]
│ [16] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Array{JuMP.ConstraintRef{JuMP.Model,MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64},MathOptInterface.GreaterThan{Float64}},JuMP.ScalarShape},1}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:272
│ [17] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [18] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [19] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [20] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [21] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [22] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [23] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [24] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [25] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [26] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [27] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Task) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:111
│ [28] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [29] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [30] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::CapturedException) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:212
│ [31] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [32] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [33] serialize_msg(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Distributed.ResultMsg) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:90
│ [34] #invokelatest#1 at ./essentials.jl:710 [inlined]
│ [35] invokelatest at ./essentials.jl:709 [inlined]
│ [36] send_msg_(::Distributed.Worker, ::Distributed.MsgHeader, ::Distributed.ResultMsg, ::Bool) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:186
│ [37] send_msg_now at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:130 [inlined]
│ [38] send_msg_now(::Sockets.TCPSocket, ::Distributed.MsgHeader, ::Distributed.ResultMsg) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:125
│ [39] deliver_result(::Sockets.TCPSocket, ::Symbol, ::Distributed.RRID, ::RemoteException) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:111
│ [40] macro expansion at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:302 [inlined]
│ [41] (::Distributed.var"#105#107"{Distributed.CallMsg{:call_fetch},Distributed.MsgHeader,Sockets.TCPSocket})() at ./task.jl:356
└ @ Distributed /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:115
Worker 5 terminated.
┌ Error: Fatal error on process 4
│ exception =
│ MethodError: no method matching write(::Sockets.TCPSocket, ::Cstring)
│ Closest candidates are:
│ write(::IO, ::Any) at io.jl:611
│ write(::IO, ::Any, !Matched::Any...) at io.jl:612
│ write(::IO, !Matched::Complex) at complex.jl:220
│ ...
│ Stacktrace:
│ [1] write(::Sockets.TCPSocket, ::Cstring) at ./io.jl:611
│ [2] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:638
│ [3] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [4] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [5] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [6] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [7] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [8] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [9] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
│ [10] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
│ [11] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
```
---
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [June 7, 2021, 2:12am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/4 "2021-06-07T02:12:36Z")
I believe this is four times the same error, namely once for each of your worker processes.
I’m a bit disappointed at Julia that (as far as I can see) there is not a single entry in the stacktrace originating from user code, so I believe what you have to do is to comment and uncomment code until you find the precise line which causes the issue.
---
### Author:  [@marouane](https://discourse.julialang.org/u/marouane)
#### Post date: [June 7, 2021, 2:15am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/5 "2021-06-07T02:15:09Z")
yes it is a four times the same error, what do you mean by comment and uncomment the code?
---
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [June 7, 2021, 2:22am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/6 "2021-06-07T02:22:27Z")
On a technical level, I mean to put a `#` at the beginning of some of your lines of code. Check your editor, there should be a shortcut to do that efficiently for many lines of code at a time. E.g. in VS Code, it’s `ctrl + /`.
The idea then is to do binary search over your code: you currently have a large piece of code which has a bug somewhere, so start narrowing down the location by commenting half your lines. If the error goes away, then you know the issue must be further down, if the error stays then the error must be further up. Continue doing this until you locate the precise line which toggles the error.
---
### Author:  [@marouane](https://discourse.julialang.org/u/marouane)
#### Post date: [June 14, 2021, 7:49am UTC](https://discourse.julialang.org/t/an-undefined-variable-error-during-parallel-computing/62482/7 "2021-06-14T07:49:36Z")
after commenting and uncommenting it, the problem falls inside the for loop exactly in the `if` statement, for instance when i comment this part:
```julia
# if i in save_iter
# push!(selected, proposed_x)
# push!(Q, qrs.prob(qq, proposed_x, mask_q2))
# end
```
i get this error
```julia
TaskFailedException:
On worker 2:
UndefVarError: current_x not defined
macro expansion at ./In[4]:29 [inlined]
#7 at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:286
#106 at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:294
run_work_thunk at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:79
macro expansion at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:294 [inlined]
#105 at ./task.jl:356
Stacktrace:
[1] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:394
[2] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
[3] remotecall_fetch(::Function, ::Int64, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
[4] remotecall_fetch at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[5] (::Distributed.var"#157#158"{typeof(+),var"#7#8",UnitRange{Int64},Array{UnitRange{Int64},1},Int64,Int64})() at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:269
Stacktrace:
[1] wait at ./task.jl:267 [inlined]
[2] fetch at ./task.jl:282 [inlined]
[3] iterate at ./generator.jl:47 [inlined]
[4] collect(::Base.Generator{Array{Task,1},typeof(fetch)}) at ./array.jl:686
[5] preduce(::Function, ::Function, ::UnitRange{Int64}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:273
[6] top-level scope at timing.jl:174
[7] include_string(::Function, ::Module, ::String, ::String) at ./loading.jl:1091
```
and when i comment this part:
`# current_x = proposed_x`
i get this following error:
```julia
TaskFailedException:
MethodError: no method matching write(::Sockets.TCPSocket, ::Cstring)
Closest candidates are:
write(::IO, ::Any) at io.jl:611
write(::IO, ::Any, ::Any...) at io.jl:612
write(::IO, ::Complex) at complex.jl:220
...
Stacktrace:
[1] write(::Sockets.TCPSocket, ::Cstring) at ./io.jl:611
[2] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:638
[3] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[4] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[5] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[6] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[7] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[8] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[9] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[10] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[11] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[12] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[13] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[14] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[15] serialize at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627 [inlined]
[16] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Array{JuMP.ConstraintRef{JuMP.Model,MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64},MathOptInterface.GreaterThan{Float64}},JuMP.ScalarShape},1}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:272
[17] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[18] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[19] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[20] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[21] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:648
[22] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627
[23] serialize_global_from_main(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Symbol) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:175
[24] #6 at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:101 [inlined]
[25] foreach at ./abstractarray.jl:2009 [inlined]
[26] serialize(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Core.TypeName) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/clusterserialize.jl:101
[27] serialize_type_data(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::DataType) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:530
[28] serialize_type(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::DataType, ::Bool) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:574
[29] serialize_any(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Any) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:644
[30] serialize at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Serialization/src/Serialization.jl:627 [inlined]
[31] serialize_msg(::Distributed.ClusterSerializer{Sockets.TCPSocket}, ::Distributed.CallMsg{:call_fetch}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:90
[32] #invokelatest#1 at ./essentials.jl:710 [inlined]
[33] invokelatest at ./essentials.jl:709 [inlined]
[34] send_msg_(::Distributed.Worker, ::Distributed.MsgHeader, ::Distributed.CallMsg{:call_fetch}, ::Bool) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:186
[35] send_msg at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/messages.jl:134 [inlined]
[36] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:389
[37] remotecall_fetch(::Function, ::Distributed.Worker, ::Function, ::Vararg{Any,N} where N) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
[38] #remotecall_fetch#146 at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[39] remotecall_fetch at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[40] (::Distributed.var"#157#158"{typeof(+),var"#15#16",UnitRange{Int64},Array{UnitRange{Int64},1},Int64,Int64})() at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:269
Stacktrace:
[1] wait at ./task.jl:267 [inlined]
[2] fetch at ./task.jl:282 [inlined]
[3] iterate at ./generator.jl:47 [inlined]
[4] collect(::Base.Generator{Array{Task,1},typeof(fetch)}) at ./array.jl:686
[5] preduce(::Function, ::Function, ::UnitRange{Int64}) at /Users/julia/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.5/Distributed/src/macros.jl:273
[6] top-level scope at timing.jl:174
[7] include_string(::Function, ::Module, ::String, ::String) at ./loading.jl:1091
```