C# Multithreading, GUI hangs while loading
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My Code below is using a backgroundWorker component. My entire GUI freezes while it loads the content tree from the database. The window even says (not responding) at the top. My desired result is to have a loading animation play while loading the data from the database... am I going at this wrong? Shouldn't the loading take place in the background, preventing the GUI from freezing up? Any ideas? ___________________________________________________________ private void bgWorker_DoWork(object sender, DoWorkEventArgs e) { LoadCompanies(); } private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { ShowLoadingAnimation(false); } private void LoadCompanies(object sender, EventArgs e) { ShowLoadingAnimation(true); this.bgWorker.RunWorkerAsync(); } private delegate void LoadCompaniesDelegate(); public void LoadCompanies() { PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria(); BindingSource src = new BindingSource(); PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria()); src.DataSource = nodes; if (pnlNavigation.InvokeRequired) { LoadCompaniesDelegate find = new LoadCompaniesDelegate(LoadCompanies); this.Invoke(find, new object[] { }); } else { pnlNavigation.ContentTree.ParentMember = "ParentId"; pnlNavigation.ContentTree.ValueMember = "Id"; pnlNavigation.ContentTree.DisplayMember = "Name"; pnlNavigation.ContentTree.PrefixMember = "CustomerNumber"; pnlNavigation.ContentTree.PostfixMember = "CityState"; pnlNavigation.ContentTree.DataSource = src; } _activeModule = "Companies"; }
Try changing the LoadCompanies method to this instead:
public void LoadCompanies(DoWorkEventArgs e)
{
PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria();BindingSource src = new BindingSource();
PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria());
src.DataSource = nodes;
e.Result = src;
}Then change your RunWorkerCompleted handler to look like this:
private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
BindingSource src = (BindingSource)e.Result;
pnlNavigation.ContentTree.ParentMember = "ParentId";
pnlNavigation.ContentTree.ValueMember = "Id";
pnlNavigation.ContentTree.DisplayMember = "Name";
pnlNavigation.ContentTree.PrefixMember = "CustomerNumber";
pnlNavigation.ContentTree.PostfixMember = "CityState";
pnlNavigation.ContentTree.DataSource = src;ShowLoadingAnimation(false);
\_activeModule = "Companies";}
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This still makes it execute on the GUI thread. One idea would be to run everything but the actual GUI stuff in the background. When BackgroundWorker finishes, you can return the data that you need to load the GUI stuff (Binding Source) through the DoWorkEventArgs.Result (which gets sent to the RunWorkerCompletedEvent when it finish DoWork). You then cast the Result to a BindingSource and do the last portion of your code (after src.DataSource = nodes; ) in the GUI thread.
I am new to C# so forgive me for not "just getting it" but this is what I have so far. I am doing something wrong because "BindingSource src = (BindingSource)e.Result;" Doesn't seem to be loading any data... Did I atleast get everything running in the background except the GUI stuff? Can you tell why I wouldn't be loading any data? Thanks in advance.
private delegate object LoadCompaniesDelegate(); public object LoadCompanies() { BindingSource src = new BindingSource(); if (pnlNavigation.InvokeRequired) { LoadCompaniesDelegate find = new LoadCompaniesDelegate(LoadCompanies); this.Invoke(find, new object[] { }); } else { PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria(); PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria()); src.DataSource = nodes; MessageBox.Show("Loaded Notes"); } return src; } private void bgWorker_DoWork(object sender, DoWorkEventArgs e) { e.Result = LoadCompanies(); } private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { BindingSource src = (BindingSource)e.Result; pnlNavigation.ContentTree.ParentMember = "ParentId"; pnlNavigation.ContentTree.ValueMember = "Id"; pnlNavigation.ContentTree.DisplayMember = "Name"; pnlNavigation.ContentTree.PrefixMember = "CustomerNumber"; pnlNavigation.ContentTree.PostfixMember = "CityState"; pnlNavigation.ContentTree.DataSource = src; _activeModule = "Companies"; MessageBox.Show("Completed"); } -
Try changing the LoadCompanies method to this instead:
public void LoadCompanies(DoWorkEventArgs e)
{
PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria();BindingSource src = new BindingSource();
PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria());
src.DataSource = nodes;
e.Result = src;
}Then change your RunWorkerCompleted handler to look like this:
private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
BindingSource src = (BindingSource)e.Result;
pnlNavigation.ContentTree.ParentMember = "ParentId";
pnlNavigation.ContentTree.ValueMember = "Id";
pnlNavigation.ContentTree.DisplayMember = "Name";
pnlNavigation.ContentTree.PrefixMember = "CustomerNumber";
pnlNavigation.ContentTree.PostfixMember = "CityState";
pnlNavigation.ContentTree.DataSource = src;ShowLoadingAnimation(false);
\_activeModule = "Companies";}
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It is still freezing the GUI. Let me know if I am doing this how you reccomended or not. Here is what I have:
private void LoadCompanies(object sender, EventArgs e) { pnlNavigation.ShowLoader(true); this.bgWorker.RunWorkerAsync(); } private delegate object LoadCompaniesDelegate(); public void LoadCompanies(DoWorkEventArgs e) { PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria(); BindingSource src = new BindingSource(); PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria()); src.DataSource = nodes; e.Result = src; } private void bgWorker_DoWork(object sender, DoWorkEventArgs e) { LoadCompanies(e); } private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { BindingSource src = (BindingSource)e.Result; pnlNavigation.ContentTree.ParentMember = "ParentId"; pnlNavigation.ContentTree.ValueMember = "Id"; pnlNavigation.ContentTree.DisplayMember = "Name"; pnlNavigation.ContentTree.PrefixMember = "CustomerNumber"; pnlNavigation.ContentTree.PostfixMember = "CityState"; pnlNavigation.ContentTree.DataSource = src; pnlNavigation.ShowLoader(false); _activeModule = "Companies"; } -
I am new to C# so forgive me for not "just getting it" but this is what I have so far. I am doing something wrong because "BindingSource src = (BindingSource)e.Result;" Doesn't seem to be loading any data... Did I atleast get everything running in the background except the GUI stuff? Can you tell why I wouldn't be loading any data? Thanks in advance.
private delegate object LoadCompaniesDelegate(); public object LoadCompanies() { BindingSource src = new BindingSource(); if (pnlNavigation.InvokeRequired) { LoadCompaniesDelegate find = new LoadCompaniesDelegate(LoadCompanies); this.Invoke(find, new object[] { }); } else { PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria(); PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria()); src.DataSource = nodes; MessageBox.Show("Loaded Notes"); } return src; } private void bgWorker_DoWork(object sender, DoWorkEventArgs e) { e.Result = LoadCompanies(); } private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { BindingSource src = (BindingSource)e.Result; pnlNavigation.ContentTree.ParentMember = "ParentId"; pnlNavigation.ContentTree.ValueMember = "Id"; pnlNavigation.ContentTree.DisplayMember = "Name"; pnlNavigation.ContentTree.PrefixMember = "CustomerNumber"; pnlNavigation.ContentTree.PostfixMember = "CityState"; pnlNavigation.ContentTree.DataSource = src; _activeModule = "Companies"; MessageBox.Show("Completed"); }Remove the --- if (pnlNavigation.InvokeRequired) { LoadCompaniesDelegate find = new LoadCompaniesDelegate(LoadCompanies); this.Invoke(find, new object[] { }); } else { -- Don't touch anything that has to do with a GUI element inside of your background worker DoWork for now... just keep what you have in RunWorkerCompleted. Currently it is taking the first path (InvokeRequired path), so the data won't be loaded into the BindingSource (since that is done in the Else) part.
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It is still freezing the GUI. Let me know if I am doing this how you reccomended or not. Here is what I have:
private void LoadCompanies(object sender, EventArgs e) { pnlNavigation.ShowLoader(true); this.bgWorker.RunWorkerAsync(); } private delegate object LoadCompaniesDelegate(); public void LoadCompanies(DoWorkEventArgs e) { PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria(); BindingSource src = new BindingSource(); PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria()); src.DataSource = nodes; e.Result = src; } private void bgWorker_DoWork(object sender, DoWorkEventArgs e) { LoadCompanies(e); } private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { BindingSource src = (BindingSource)e.Result; pnlNavigation.ContentTree.ParentMember = "ParentId"; pnlNavigation.ContentTree.ValueMember = "Id"; pnlNavigation.ContentTree.DisplayMember = "Name"; pnlNavigation.ContentTree.PrefixMember = "CustomerNumber"; pnlNavigation.ContentTree.PostfixMember = "CityState"; pnlNavigation.ContentTree.DataSource = src; pnlNavigation.ShowLoader(false); _activeModule = "Companies"; }Stick in some debug statements to see where it is slowing down on.
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Stick in some debug statements to see where it is slowing down on.
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Remove the --- if (pnlNavigation.InvokeRequired) { LoadCompaniesDelegate find = new LoadCompaniesDelegate(LoadCompanies); this.Invoke(find, new object[] { }); } else { -- Don't touch anything that has to do with a GUI element inside of your background worker DoWork for now... just keep what you have in RunWorkerCompleted. Currently it is taking the first path (InvokeRequired path), so the data won't be loaded into the BindingSource (since that is done in the Else) part.
Thank you Phil. I still get the (Not Responding) for a couple seconds when it gets to "pnlNavigation.ContentTree.DataSource = src;" This is a lot of data to load. Since it is taking the most time, shouldn't that part be inside bgWorker_DoWork? ... but it cannot because it is updating the GUI ... so I don't konw what to do.
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Remove the --- if (pnlNavigation.InvokeRequired) { LoadCompaniesDelegate find = new LoadCompaniesDelegate(LoadCompanies); this.Invoke(find, new object[] { }); } else { -- Don't touch anything that has to do with a GUI element inside of your background worker DoWork for now... just keep what you have in RunWorkerCompleted. Currently it is taking the first path (InvokeRequired path), so the data won't be loaded into the BindingSource (since that is done in the Else) part.
What do you think about this explanation? The freezing is because the control is being filled out by the data source, and the only thread allowed to do that is the UI. So, if your data source is large there isn't a way around the 2 seconds pause... unless... You could manually fill out your control by looping over the data source yourself, and every 10 or so, do a DoEvents() call to keep the UI fresh.
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It is still freezing the GUI. Let me know if I am doing this how you reccomended or not. Here is what I have:
private void LoadCompanies(object sender, EventArgs e) { pnlNavigation.ShowLoader(true); this.bgWorker.RunWorkerAsync(); } private delegate object LoadCompaniesDelegate(); public void LoadCompanies(DoWorkEventArgs e) { PROSOCO.Library.Companies.Criteria criteria = PROSOCO.Library.Companies.Criteria.GetCriteria(); BindingSource src = new BindingSource(); PROSOCO.Library.Companies.Nodes nodes = PROSOCO.Library.Companies.Nodes.GetNodes(criteria.NodeCriteria()); src.DataSource = nodes; e.Result = src; } private void bgWorker_DoWork(object sender, DoWorkEventArgs e) { LoadCompanies(e); } private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { BindingSource src = (BindingSource)e.Result; pnlNavigation.ContentTree.ParentMember = "ParentId"; pnlNavigation.ContentTree.ValueMember = "Id"; pnlNavigation.ContentTree.DisplayMember = "Name"; pnlNavigation.ContentTree.PrefixMember = "CustomerNumber"; pnlNavigation.ContentTree.PostfixMember = "CityState"; pnlNavigation.ContentTree.DataSource = src; pnlNavigation.ShowLoader(false); _activeModule = "Companies"; }To eliminate possibilities, temporarily comment all code inside RunWorkerCompleted handler. Does it still freeze?
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What do you think about this explanation? The freezing is because the control is being filled out by the data source, and the only thread allowed to do that is the UI. So, if your data source is large there isn't a way around the 2 seconds pause... unless... You could manually fill out your control by looping over the data source yourself, and every 10 or so, do a DoEvents() call to keep the UI fresh.
justin.moses wrote:
So, if your data source is large there isn't a way around the 2 seconds pause... unless...
If your data set is too large to be displayed all at once, your best bet is filling the dataset a few rows at a time, preferrably in the Application.Idle event handler. p.s. don't use DoEvents(). It's evil, trust me.
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