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Performance. Practical Recommendations

Even the best performing component can be hindered by incorrect use. Below we provide practical recommendations on what should be used or avoided in application programming. Following the tips below you will be able to create applications with the same efficiency as this demo application. We also provide source codes for this example to show how easy it is.
It is supposed that programmers already know general principles of application design. Nevertheless, we shall provide some useful links for better understanding of .Net environment and tools for writing managed code: Writing Faster Managed Code: Know What Things Cost
It is necessary to pay attention to grid characteristics in different working modes, to evaluate data volume to be displayed and to find a relevant chart for better understanding of grid use.
Have only one message loop per application. Don’t create grids in different threads.
Let us assume that the computer resources are not limitless. Theoretically the maximum performance can be obtained if the number of threads equals to the number of processor cores. While a lot of threads are creating, they aren’t working in parallel. In this case cores allocate time slices to threads based on their priority and consistently perform context switches (context switch is relatively expansive operation). Note, maximum time slice is about 10-15 msec.
We have also take into account that each control paints its content in the GDI/GDI+ device (via the Graphics object). While painting from one thread all others wait for GDI device to perform painting in its turn. Therefore if we start many message loops – it doesn’t mean that we accelerate the application. In other words the application losses time on context switches and on drawing in GDI device.
From our point of view the application should have only one message pump. Windows has additional mechanisms to optimize content drawing and we are not sure that they work in case of multithreaded environment. Of course, business logic can work in any thread, but the graphical thread should be only one in the application.
Use MethodInvoker to synchronize threads.
In multi-threaded applications every call should be synchronized with the main thread containing windows message loop. Both Control.Invoke and Control.BeginInvoke methods may accept different delegate types and their parameters. However, this causes a serious performance issue as they call Delegate.DynamicInvoke(params object[] args), which in turn uses low-performance reflection. At the same time, for some delegates such as EventHandler, MethodInvoker and WaitCallback the code is called directly. In the time of code execution the delegate is checked for belonging to one of the above types with specified number of parameters, and if it doesn’t – DynamicInvoke() is called.
Use objects of arbitrary classes instead of collections of values of string[] type, etc. It is more convenient and objects of arbitrary classes consume less memory than string collections.
Don’t format values directly in data objects, i.e. if an object property is to return date, this field should return DateTime object type instead of string type. Use data formatting if needed. If properties return strings, they can be compared incorrectly during data sorting. Besides, comparing two strings requires more CPU resources than comparing two DateTime objects.
This working principle is the same for all grids of all vendors. The main issue is that PropertyDescriptor.GetValue() method uses reflection. NetGrid has an optimization that enables it to receive notifications from INotifyPropertyChanged/IBindingList without calling data object getters. Values are required only at the time of painting and only for visible cells. If the grid has a lot of rows, most of them are invisible and this approach significantly saves CPU resources. It is worth considering in application development. As an example, let’s review subscription to Grid.RowUpdated event:
When updating data in real time in applications, the grid stores highlighting information for each updated cell. This default behavior causes serious consumption of memory resources in addition to CPU resource consumption due to processing large volume of information. As most updates can occur outside the visible area, the programmer can save CPU resources by using the new property.
When this optimization is used, vertical scrolling may bring rows without cell highlighting information to the visible area and the user will not see cell highlights that were made before rows get to visible area of the grid. This concerns only highlighting information, while text and other cell content will display correctly. The programmer should decide whether to use such optimization or not.
Be very careful about creating temporary objects as it may result in memory pressure and make garbage collector collect unused objects more frequently. Please note that when garbage is collected, all application threads are temporarily stopped.
Don’t use finalizers in objects unless necessary.
We hope that these simple recommendations will help you create efficient and high-performing applications.