Segfault when exiting Julia after replacing a JuliaItemModel

Hi,

My Qt app runs fine, but then after closing it there is segfault when exiting the Julia session.

As discussed here

MWE 1:

using QML

# const qml_file = joinpath(pwd(), "code", "qml", "test.qml")

function update_props()
    props["fruits"] = fruits2
end

function main(qml_file, props)
    loadqml(qml_file, props = props)
    exec()
end

mutable struct Fruit
    name::String
    cost::Float64
end

fruits  = JuliaItemModel([Fruit("apple", 1.0), Fruit("orange", 2.0)])
fruits2 = JuliaItemModel([Fruit("banana", 1.0), Fruit("pear", 2.0)])

props = JuliaPropertyMap("fruits" => fruits)

@qmlfunction update_props

# main(qml_file, props)


mktempdir() do folder
            path = joinpath(folder, "test.qml")
            write(path, """
                  import QtQuick
                  import QtQuick.Controls
                  import QtQuick.Layouts
                  import org.julialang

                  ApplicationWindow {
                      id: mainWin
                      title: "My Application"
                      width: 400
                      height: 400
                      visible: true
                    
                      ColumnLayout{
                        anchors.fill: parent
                    
                          Button {
                              height: 200
                              Layout.fillWidth: true
                              text: "Update Fruit"
                              onClicked: { 
                                  Julia.update_props()
                                  console.log("Value:", props.fruits) 
                              }
                         }
                          ListView {
                              model: props.fruits
                              Layout.fillHeight: true
                              Layout.fillWidth: true
                              delegate: Row {
                                  Text {
                                      text: name
                                  }
                              }
                          }
                      }
                  }
                  """)
            main(path, props)
          end

MWE 2:

using QML

# const qml_file = joinpath(pwd(), "code", "qml", "test.qml")

function update_props()
    props["fruits"] = fruits2
end

function main(qml_file, props)
    loadqml(qml_file, props = props)
    exec()
end

mutable struct Fruit
    name::String
    cost::Float64
end

fruits  = JuliaItemModel([Fruit("apple", 1.0), Fruit("orange", 2.0)])
fruits2 = JuliaItemModel([Fruit("banana", 1.0), Fruit("pear", 2.0)])

props = JuliaPropertyMap("fruits" => fruits)

@qmlfunction update_props

# main(qml_file, props)


mktempdir() do folder
            path = joinpath(folder, "test.qml")
            write(path, """
                  import QtQuick
                  import QtQuick.Controls
                  import QtQuick.Layouts
                  import org.julialang

                  ApplicationWindow {
                      id: mainWin
                      title: "My Application"
                      width: 400
                      height: 400
                      visible: true

                      Connections {
                        target: button
                        // onClicked: Julia.update_props()
                        function onClicked() { Julia.update_props() }
                      }
                    
                      ColumnLayout{
                        anchors.fill: parent
                    
                          Button {
                              id: button
                              height: 200
                              Layout.fillWidth: true
                              text: "Update Fruit"
                              // onClicked: { 
                              //     Julia.update_props()
                              //     console.log("Value:", props.fruits) 
                              // }
                         }
                          ListView {
                              model: props.fruits
                              Layout.fillHeight: true
                              Layout.fillWidth: true
                              delegate: Row {
                                  Text {
                                      text: name
                                  }
                              }
                          }
                      }
                  }
                  """)
            main(path, props)
          end

It isn't clear whether this is misusing the package or a bug.

Thanks.

For completeness:

julia> versioninfo()
Julia Version 1.11.5
Commit 760b2e5b739 (2025-04-14 06:53 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 4 × Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, skylake)
Threads: 1 default, 0 interactive, 1 GC (on 4 virtual cores)

julia> Pkg.status()
  [336ed68f] CSV v0.10.15
  [1f15a43c] CxxWrap v0.16.2
  [3b531cbf] DataConvenience v0.3.6
  [a93c6f00] DataFrames v1.7.0
  [c601a237] Interact v0.10.5
  [510215fc] Observables v0.5.5
  [d96e819e] Parameters v0.12.3
  [2db162a6] QML v0.9.2
  [2913bbd2] StatsBase v0.34.4
  [f3b207a7] StatsPlots v0.15.7

I can reproduce the issue.

This is a crosspost of my workaround from the discourse thread.

This works. First clear the array in QML, then push to it from Julia:

using QML

# const qml_file = joinpath(pwd(), "code", "qml", "test.qml")

function update_props()
    props["fruits"] = fruits2
end

# First clear props in QML
function update_props()
    [push!(props["fruits"], fruits2[i]) for i in 1:length(fruits2)]
end


function main(qml_file, props)
    loadqml(qml_file, props = props)
    exec()
end

mutable struct Fruit
    name::String
    cost::Float64
end

fruits  = JuliaItemModel([Fruit("apple", 1.0), Fruit("orange", 2.0)])
fruits2 = JuliaItemModel([Fruit("banana", 1.0), Fruit("pear", 2.0)])

props = JuliaPropertyMap("fruits" => fruits)

@qmlfunction update_props

# main(qml_file, props)


mktempdir() do folder
            path = joinpath(folder, "test.qml")
            write(path, """
                  import QtQuick
                  import QtQuick.Controls
                  import QtQuick.Layouts
                  import org.julialang

                  ApplicationWindow {
                      id: mainWin
                      title: "My Application"
                      width: 400
                      height: 400
                      visible: true
                    
                      ColumnLayout{
                        anchors.fill: parent
                    
                          Button {
                              height: 200
                              Layout.fillWidth: true
                              text: "Update Fruit"
                              onClicked: {
                                  // First clear then update from julia
                                  props.fruits.clear() 
                                  Julia.update_props()
                              }
                         }
                          ListView {
                              model: props.fruits
                              Layout.fillHeight: true
                              Layout.fillWidth: true
                              delegate: Row {
                                  Text {
                                      text: name
                                  }
                              }
                          }
                      }
                  }
                  """)
            main(path, props)
          end

Still there should be a warning instead of that segfault.

I confirm that I can reproduce this, it's probably a bug related to not disconnecting notification functions when changing the property, so it's a QML.jl bug, not wrong usage :)

Add QJSEngine and ownership method

Keep Julia ownership when setting values in a JuliaPropertyMap

Fixed in QML.jl v0.13.2.

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Segfault when exiting Julia after replacing a JuliaItemModel #218

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Segfault when exiting Julia after replacing a JuliaItemModel #218

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ufechner7 commented on May 6, 2025

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