Improve perceived WPF app startup time

问题

I have a WPF database viewer application: It's a simple main window containing a user control with a data grid showing the data extracted from an SQLite database.
The problem is that this application takes 6 seconds to start until it is usable.

I tried building the user control (and doing all the data loading) in the constructor of the main window:
The splash screen will be shown 5s this way, then followed by 1s of empty main window until the application is ready to be used.
Users said that it takes too long until something (visually) happens.

I then moved the user control creation (and data loading) into the Loaded event handler of the main window: The splash screen will be shown 3s, followed by 3s of empty main window until the application is ready.
Users said that it is "better", but don't like the fact that a half finished main window is shown in disabled state for so long.

Is there some general advice to be found about perceived application load time or are there any other recommendations about how this situation can be improved?
I believe ideally the main window would be shown as fast as possible, along with some hour glass or spinner until the data is loaded. But then I cannot just move the user control creation into a background worker as this would be done on the wrong thread.

Does anybody have any suggestions to this problem?

Edit:
Note that right now I've just assigned a LINQ-to-EF query as the grid data source.
One possible improvement may be to load this data into a data table in background and assign it only once loaded...

Edit2: I'm using .net 4 with System.Data.SQLite and EF4 to load the data. There are more or less 4000 rows and 30 columns.

回答1:

Load your data asynchronous. Present something nice on the GUI for the user while loading. The following code can help you with this:

BackgroundWorker bgWorker = new BackgroundWorker() { WorkerReportsProgress=true};  
bgWorker.DoWork += (s, e) => {      
    // Load here your file/s      
    // Use bgWorker.ReportProgress(); to report the current progress  
};  
bgWorker.ProgressChanged+=(s,e)=>{      
    // Here you will be informed about progress and here it is save to change/show progress. 
    // You can access from here savely a ProgressBars or another control.  
};  
bgWorker.RunWorkerCompleted += (s, e) => {      
// Here you will be informed if the job is done. 
// Use this event to unlock your gui 
};  
bgWorker.RunWorkerAsync();

The app is not faster but it seems to be much faster because the GUI is immediately visible and responsive. Maybe you also can show the user a part of the loaded data while loading the rest. Use the ProgressChanged-event for doing this.

Update

I'm not sure if I understand your problem right. If your problem is not the time data needs to be loaded, then something is odd in your application. WPF is IMO very fast. Control-creation does not takes a lot of time. I visualize much bigger lists as you mention in some milliseconds.

Try to look if you have something in your UI that hinders the DataGrid to virtualize the Items. Maybe you have a proplem there. To analyse WPF apps, I can recommend you the WPF Profiling Tools.

回答2:

The most obvious thing you can do is to profile your application and find the bottlenecks in start up time. It sounds like the most likely culprit will be the loading of data from your database.

One lesson I've learnt is that if you're using an ORM, when loading large datasets if you favour POCO (Plain Old CLR/C# Objects) over ORM-generated database entities (see example below), the load time will be a lot faster and RAM usage will be significantly decreased too. The reason for this is that EF will try to load the entire entity (i.e. all of it's fields) and possibly a whole load of data related to your entities, most of which you won't even need. The only time you really need to work directly with entities is when you're doing insert/update/delete operations. When reading data you should only get fields that your application needs to display and/or validate.

If you follow the MVVM pattern, the above architecture isn't hard to implement.

Example of loading data into POCOs with EF:

var query = from entity in context.Entities
                select new EntityPoco
                {
                    ID = entity.ID,
                    Name = entity.Name
                };

return query.ToList();

POCOs are very simple classes with autoproperties for each field.

We usually have repositories for each entity in our applications and each repository is responsible for getting/updating data related to that entity. The view models have references to the repositories they need so they don't use EF directly. When users make changes that need to be persisted, we use other methods in the repository that then load only a subset of entities (i.e. the ones the user changed) and apply the necessary updates - with some validation done by the viewmodel and possibly other validation going on in the DB via constraints/triggers, etc.

回答3:

There are many reasons for this.

1) Deployment machine might have fairly low configuration.
2) In-Proper or problem with data binding.

Possible solutions would be:
1) Lazy load the data
2) Optimize the performance. http://msdn.microsoft.com/en-us/library/aa970683.aspx

I had saw applications render 5M records less than a second in wpf.

PS:One more least possible reasons may be 30 columns, due to column order access.

来源：https://stackoverflow.com/questions/4724774/improve-perceived-wpf-app-startup-time

标签

.net

wpf

performance

app-startup