Question

I’m developing a GTK# application using a SOAP service to get the data. Errors are occurring on retrieving items and putting them in a Gtk.ComboBox.

Types of errors seen:

• gmem.c:170: failed to allocate x bytes, followed by SIGTRAP/SIGSEV/whatever
• glibc detected * /usr/bin/mono: double free or corruption (fasttop): 0x00007f27100e85a0 *
  Gdk:ERROR:gdkregion-generic.c:1110:miUnionNonO: assertion failed: (y1 < y2)
  followed by SIGIOT
  *just a SIGSEGV with a long stracktrace

I do also see these quite often:

• (KvkManager:11471): Pango-WARNING **: Invalid UTF-8 string passed to pango_layout_set_text()
• (KvkManager:11506): Gtk-WARNING **: gtktreemodel.c:2114: bad row reference, proxy has no outstanding row references

This is the main part of my code:

using System;
using Gtk;
using KvkWsProxy;

public partial class MainWindow: Gtk.Window
{
    private KvkSoapServerService kvkProxy;
    private NodeStore productsStore;

    protected Gdk.PixbufAnimation loadingTrobber;

    public MainWindow (): base (Gtk.WindowType.Toplevel)
    {
        Build ();

        this.tabs.CurrentPage = 0;

        this.loadingTrobber = new Gdk.PixbufAnimation("ajax-loader.gif");

        this.productsStore = new Gtk.NodeStore(typeof(KvkManager.SimpleProductTreeNode));

        this.kvkProxy = new KvkSoapServerService();
        this.kvkProxy.getSimpleProductsCompleted += this.putProducts;
        this.kvkProxy.getCollectionsCompleted += this.putProductCollections;
        this.kvkProxy.getTypesCompleted += this.putProductTypes;

        this.productsList.NodeStore = productsStore;
        this.productsList.AppendColumn("Nummer", new Gtk.CellRendererText(), "text", 0);
        this.productsList.AppendColumn("Naam", new Gtk.CellRendererText(), "text", 1);
        this.productsList.AppendColumn("Prijs", new Gtk.CellRendererText(), "text", 2);
        this.productsList.ShowAll();

        this.getProductCollections();
        this.getProductTypes();
    }

    protected void OnDeleteEvent (object sender, DeleteEventArgs a)
    {
        Application.Quit ();
        a.RetVal = true;
    }

    protected void putProductCollections(object sender, getCollectionsCompletedEventArgs args)
    {       
        this.productCollectionsComboBox.Clear();

        CellRendererText cell = new CellRendererText();
        this.productCollectionsComboBox.PackStart(cell, false);
        this.productCollectionsComboBox.AddAttribute(cell, "markup", 1);

        ListStore store = new ListStore(typeof(int), typeof(string));
        this.productCollectionsComboBox.Model = store;
        store.AppendValues(-1, "<span font-style=\"italic\">alle collecties</span>");

        foreach(Product_ProductCollection collection in args.Result)
        {
            store.AppendValues(collection.id, collection.name);
        }

        this.productCollectionsComboBox.Active = 0;
        this.productCollectionsComboBox.Sensitive = true;
        this.getCollectionsAnimation.Visible = false;
    }

    protected void putProductTypes(object sender, getTypesCompletedEventArgs args)
    {
        ... like putProductCollections() ...
    }

    protected void OnSearchButtonClicked (object sender, System.EventArgs e)
    {
        this.productSearchButton.Sensitive = false;
        this.searchAnimation.PixbufAnimation = this.loadingTrobber;
        this.searchAnimation.Visible = true;

        productsStore.Clear();

        this.kvkProxy.getSimpleProductsAsync();
    }

    protected void putProducts(object sender, getSimpleProductsCompletedEventArgs args)
    {       
        foreach(Product_SimpleProduct product in args.Result)
        {
            productsStore.AddNode(new KvkManager.SimpleProductTreeNode(product));
        }

        this.productSearchButton.Sensitive = true;
        this.searchAnimation.Visible = false;
    }

    protected void getProductCollections()
    {
        this.productCollectionsComboBox.Sensitive = false;
        this.getCollectionsAnimation.PixbufAnimation = this.loadingTrobber;
        this.getCollectionsAnimation.Visible = true;

        this.kvkProxy.getCollectionsAsync();
    }

    protected void getProductTypes()
    {
        ... like putProductCollections() ...
    }

    protected void getProductSizegroups()
    {
        ... like putProductCollections() ...
    }

    protected void getProductBrands()
    {
        ... like putProductCollections() ...
    }
}

You can download the whole project on http://home.vdslikke.net:8090/~johan/KvkManager.zip.

Versions of my software:

• MonoDevelop 2.8.1
• Mono 2.10.5 (tarball Mon Sep 5 19:35:47 UTC 2011) (64-bit)
• GTK 2.24.8 (GTK# 2.12.0.0)

If there is any information you need to help me with this problem, please let me know.

Answer 1

I found out what I was doing wrong here

The thread that happens to run the event loop is said to “own” Gtk. This means that all Gtk operations should be perfomed from this thread and no other thread. Failure to restrict the use of Gtk to this thread will result in unpredictable behavior, and most often will lead to a crash.

After wrapping all GUI operations in Gtk.Application.Invoke() I get no errors anymore.