Error when navigating Tree View too quickly about anolis

[Dobby233Liu]

creation date = 2009-03-04T10:48:35.51-08:00

I've experienced these quite alot some time ago... my solution for fixing it was implementing a pool of threads. In my app there are about 7-8 concurrent threads and some of course will require access to the UI.

When working with the tree from another thread you should go for something like if (this.InvokeRequired) ... and use BeginUpdate() and EndUpdate() when using data from the tree.

This is my ThreadMgr class, feel free to adapt it to your needs.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Windows.Forms;
using System.Collections;

namespace LUR.Interop
{
    public class ThreadMgr : IDisposable, IEnumerable
    {
        private List<Thread> Pool = null;

        public ThreadMgr()
        {
            Pool = new List<Thread>();
        }

        public int Clean()
        {
            int Running = 0;
            if (Pool == null)
                return Running;

            for (int i = 0; i < Pool.Count; i++)
            {
                if (Pool[i].IsAlive)
                    Running++;
                else
                    Pool.Remove(Pool[i--]);
            }
            return Running;
        }

        public bool this[string Item, ThreadStart x]
        {
            set
            {

                Thread t = this[Item];
                if (t == null)
                {
                    try
                    {
                        if (x == null)
                            throw new System.ArgumentNullException();

                        t = this[Item] = new Thread(x);
                        t.TrySetApartmentState(ApartmentState.MTA);
                        if (value)
                            t.Start();
                    }
                    catch (System.ArgumentNullException)
                    {
                        Console.WriteLine("ThreadMgr: null or malformed parameterized thread start invoked.");
                    }
                    catch (System.Threading.ThreadStateException msg)
                    {
                        Console.WriteLine("ThreadMgr: failed " + msg.Message + " at " + msg.Source + " in " + Item + " context");
                    }
                    catch (Exception msg)
                    {
                        Console.WriteLine("ThreadMgr: unrecoverable fault caused by " + msg.Message + " in " + msg.StackTrace);
                    }
                }
                else
                {
                    // Ionutz: testeaza-ma!
                    MessageBox.Show(null, Item + " context is already locked or request is null; cannot instanciate.\n" +
                        "You may be trying to re-execute the same operation before waiting the previous attempt to complete", 
                        "Threading Manager", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                }
            }
        }

        public Thread this[string Item]
        {
            get
            {
                if ((Pool != null) && (Pool.Count > 0))
                {
                    foreach (Thread t in Pool)
                        if (t.Name == Item)
                            return t;
                }
                return null;
            }
            set
            {
                if (Pool == null)
                    Pool = new List<Thread>();
                
                try
                {
                    Pool.Add(value);
                    value.Name = Item;
                }
                catch (Exception msg)
                {
                    Console.WriteLine("ThreadMgr: " + msg.Message + "; " + value.Name + " override attempt with " + Item + " denied.");
                }
            }
        }

        public void Sync(string Item)
        {
            Thread t = this[Item];
            try
            {
                if (t.IsAlive)
                    t.Join();
            }
            catch { }
        }

        #region IDisposable Members

        public void Dispose()
        {
            if ((Pool != null) && (Pool.Count > 0))
            {
                for (int i = 0; i < Pool.Count; i++)
                {
                    if (Pool[i].IsAlive)
                        Pool[i].Abort();

                    Pool.Remove(Pool[i--]);
                }
            }
        }

        #endregion

        public void Recycle(string id)
        {
            try
            {
                foreach (Thread Pooled in Pool)
                {
                    if (Pooled.Name.Contains(id))
                    {
                        Pooled.Abort();
                        break;
                    }
                }
            }
            catch
            { }
        }


        #region IEnumerable Members

        public IEnumerator GetEnumerator()
        {
            foreach (Thread t in Pool)
            {
                yield return t;
            }
        }

        #endregion
    }
}

[Dobby233Liu]

closed date = 2009-04-10T14:29:58.64-07:00

I solved this by making the PopulateResourceType method check if the .CancelAsync method had been called. Additionally there are two layers of threads from ShowResourceType and PopulateResourceType.