Speed Optimization in ASP.NET 2.0 Web Applications - Part 2
Summary
In part 1 of this tutorial we
mentioned five
areas under which we can classify the techniques that can be used to optimize web
application performance. In part 1 we explained the fist two areas
only. Here we are going to cover the following remaining 3 sections:
- Page and
server controls
- Web applications
- Coding practices
Page and Server Controls
The following topics give you an idea about
how to use pages and controls efficiently in your web application:
Use HTML controls whenever possible
HTML controls is lighter than server controls especially if you
are using server controls with its default properties. Server controls generally is
easier to use than HTML controls, and on the other side they are slower than HTML
controls. So, it is recommended to use HTML controls whenever possible and avoid
using unnecessary server controls.
Avoid round trips to server whenever possible
Using server controls will extensively increase round trips to the server
via their post back events which wastes a lot of time. You typically need to avoid these
unnecessary round trips or post back events as possible. For example, validating
user inputs can always (or at least in most cases) take place in the client side.
There is no need to send
these inputs to the server to check their validity. In general you should avoid code that
causes a round trip to the server.
The Page.IsPostBack Property
The Page.IspostBack Boolean property indicates whether this
page is loaded as a response to a round trip to the server, or it is being
loaded for the first time. This property helps you to write the code needed for the first time the page is loaded, and avoiding
running this same code each
time the page is posted back. You can use this property efficiently in the page_load event.
This event is executed each time a page is loaded, so you can
use this property conditionally to avoid unnecessary re-running of certain
code.
Server Control's AutoPostBack Property
Always set this property to false except when you really need to turn
it on. This property automatically post back to the server after some action
takes place depending on the type of the control. For example, in the Text Control
this property automatically post back to the server after the text is modified
which is a great deal of processing cost and hence much slower performance and
most importantly a poor user experience.
Leave Buffering on
It is important to leave page buffering in its on state to
improve your page speed, unless you have a serious reason to turn it off.
Server Controls View State
Server control by default saves all the values of its properties
between round trips, and this increases both page size and processing
time which is of course an undesired behavior. Disable the server control view state whenever possible. For example, if
you bind data to a server control each time the page is posted back, then it is useful to disable the control's view state property.
This reduces page size
and processing time.
Methods for redirection
There are many ways you can use to redirect a user from the
current page to another one in the same application, however the most efficient
methods to do this are: the Server.Transfer method or cross-page posting.
Web Applications
The following topics give you some tips about
how to make an efficient web application:
Precompilation
When an already deployed ASP.NET web application page is requested for
the first time, that page needs to be compiled (by the server) before the user gets a response.
The compiled page or code is then cached so that we need not to compile it again for
the coming requests. It is clear
that the first user gets a slow response than the following users. This scenario
is repeated for each web page and code file within your web site.
When using precompilation then the ASP.NET entire web application pages and code
files will be compiled ahead. So, when a user requests a page from this web
application he will get it in a reasonable response time whatever he is the
first user or not.
Precompiling the entire web application before making it available to users provides
faster response times. This is very useful on frequently updated
large web applications.
Encoding
By default ASP.NET applications use UTF-8 encoding. If your
application is using ASCII codes only, it is preferred to set your encoding to ASCII
to improve your application performance.
Authentication
It is recommended to turn authentication off when you do not
need it. The authentication mode for ASP.NET applications is windows mode. In
many cases it is preferred to turn off the authentication in the 'machin.config'
file located on your server and to enable it only for
applications that really need it.
Debug Mode
Before deploying your web application you have to disable the debug
mode. This makes your deployed application faster than before. You can disable
or enable debug mode form within your application's 'web.config' file under
the 'system.web' section as a property to the 'compilation' item. You can set it to
'true' or 'false'.
Coding Practices
The following topics give you guidelines to write efficient
code:
Page Size
Web page with a large size consumes more bandwidth
over the network during its transfer. Page size is affected by the
numbers and types of controls it contains, and the number of images
and data used to render the page. The larger the slower, this is the
rule. Try to make your web pages small and as light as possible. This
will improve response time.
Exception Handling
It is better for your application in terms of performance to
detect in your code conditions that may cause exceptions instead of relying on
catching exceptions and handling them. You should avoid common exceptions like null
reference, dividing by zero , and so on by checking them manually in your
code.
The following code gives you two examples: The first one uses exception handling
and the second tests for a condition. Both examples produce the same result,
but the performance of the first one suffers significantly.
| |
8 ' This is not recommended.
9 Try
10 Output = 100 / number
11 Catch ex As Exception
12 Output = 0
13 End Try
14
15 ' This is preferred.
16 If Not (number = 0) Then
17 Output = 100 / number
18 Else
19 Output = 0
20 End If
|
|
Garbage Collector
ASP.NET provides automatic garbage collection and memory
management. The garbage collector's main task is to allocate and release memory
for your application. There are some tips you can take care of when you writing
your
application's code to make the garbage collector works for your benefit:
Avoid using objects with a Finalize sub as possible and avoid freeing
resources in Finalize functions.
Avoid allocating too much memory per web page because the
garbage collector will have to do more work for each request and this
increases CPU utilization (not to mention you can go out of memories in
larger web applications)
Avoid having unnecessary pointers to objects because this makes
these objects alive
until you free them yourself within your code not in an automatic way.
Use Try / Finally
If you are to use exceptions anyway, then always use
a try / finally block to handle your
exceptions. In the finally section you can close your resources if an
exception occurred or not. If an exception occurs, then the finally section
will clean up your resources and frees them up.
String Concatenation
Many string concatenations are time consuming operations. So, if
you want to concatenate many strings such as to dynamically build some HTML or
XML
strings then use the System.Text.StringBuilder object instead of system.string data type. The append method of the StringBuilder class is more
efficient than concatenation.
Threading
If your application contains some operation that
consumes time and resources, then instead of blocking the application
flow awaiting for this process or operation to be finished it is
recommended to create a separate thread for this blocking operation. By
threading you will save your application normal flow from delays. Examples of time consuming operations that
can be moved to another thread other than the main program thread
are: querying on a database and waiting for results, and extensive
IO operations.
For further
information
Refer to the online copy of Microsoft Developers Network at
http://msdn.microsoft.com or use
your own local copy of MSDN.
|
