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Tips to improve Performance of Web Application

, 4 Mar 2007
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Improve Performance of Web Application

Introduction

This article list out Performance tips to improve performance of Web applications . I have divided total tips into 3 modules based on where we use. 1.Web.config. 2. Web applications. 3. Database operations.

In Web.config

1. Turn off Tracing unless until required.

<trace enabled="false" pageOutput="false" traceMode="SortByTime" localOnly="true" />

2. Turn off session state in web.config file or at least for a page if there is no sessions.

3 set debug=false

<compilation defaultLanguage="c#" debug="false">

4. Increase the Pool "Packet size" for transferring large blob or image fields

In connection string set "Packet Size= Required number". Performance decreases if the Packet size is huge for small amount of data transfers.

In web applications

1. Per-Request Caching

2. Cache API (Data set)

3. Background Processing (sending mails through timer 5-min)

4. Page Output Caching

5. Run IIS 6.0

6. Use Gzip Compression

7. Disable View State of a Page or Datagrid if possible.

An example of View State might be a long form that users must fill out: if they click Back in their browser and then return, the form will remain filled. When this functionality isn't used, this state eats up memory and performance. Perhaps the largest performance drain here is that a round-trip signal must be sent across the network each time the page is loaded to update and verify the cache. Since it is on by default, you will need to specify that you do not want to use View State with

<@% EnabledViewState = false %>.

8. Use Response.Redirect (".aspx",false) instead of response.redirect(".aspx"). It

Reduces CLR Exceptions count.

9 String Builder in place of string when ever needed

When a string is modified, the run time will create a new string and return it, leaving the original to be garbage collected. Most of the time this is a fast and simple way to do it, but when a string is being modified repeatedly it begins to be a burden on performance: all of those allocations eventually get expensive. To solve this Use String Builder when ever needed.

10. Fragment caching

Cache the "User controls" whenever those are repeated in several forms in a project.

11. Avoid Throwing Exceptions. It is very expensive.

Finding and designing away exception-heavy code can result in a decent perf win. Bear in mind that this has nothing to do with try/catch blocks: you only incur the cost when the actual exception is thrown. You can use as many try/catch blocks as you want. Using exceptions gratuitously is where you lose performance. For example, you should stay away from things like using exceptions for control flow.

12. Change into Release mode

Select the Release mode before making the final Build for your application. By default it is in Debug mode.

13. Use Finally Method to kill resources.

Ideal Finally block:

If Not SqlDr Is Nothing Then SqlDr.Close() End If

If Not sqlcon Is Nothing Then Sqlcon.Close() End If

14. Validate all Input received from the Users.

Use Client Side Validations as much as possible. However, do a check at the Server side too to avoid the infamous Javascript disabled scenarios.

15. Avoid Recursive Functions / Nested Loops

16. Enable Option Strict and Option Explicit for your pages.

With Option Strict on, you protect yourself from inadvertent late binding and enforce a higher level of coding discipline.

Option Explicit is less restrictive than Option Strict, but it still forces programmers to provide more information in their code. Specifically, you must declare a variable before using it.

17. Use early binding in Visual Basic or JScript code.

Visual Basic 6 does a lot of work under the hood to support casting of objects, and many programmers aren't even aware of it. In Visual Basic 7, this is an area that out of which you can squeeze a lot of performance. When you compile, use early binding. This tells the compiler to insert a Type Coercion is only done when explicitly mentioned. This has two major effects:

a. Strange errors become easier to track down.

b. Unneeded coercions are eliminated, leading to substantial performance improvements.

When you use an object as if it were of a different type, Visual Basic will coerce the object for you if you don't specify. This is handy, since the programmer has to worry about less code.

18. Use Response.Write for String concatenation

Use the HttpResponse.Write method in your pages or user controls for string concatenation.

This method offers buffering and concatenation services that are very efficient. If you are performing extensive concatenation, however, the technique in the following example, using multiple calls to Response.Write, is faster than concatenating a string with a single call to the Response.Write method.

19. Avoid unnecessary round trips to the server

a. Implement Ajax UI whenever possible. The idea is to avoid full page refresh and only update the portion of the page that needs to be changed. I think Scott's article gave great information on how to implement Ajax Atlas and <atlas:updatepanel> control.

b. Use Client Side Scripts. Client site validation can help reduce round trips that are required to process user's request. In ASP.NET you can also use client side controls to validate user input.

c. Use Page.ISPostBack property to ensure that you only perform page initialization logic when a page first time loaded and not in response to client postbacks.

If Not IsPostBack Then

LoadJScripts()

EndIf

d. In some situations performing postback event handling are unnecessary. You can use client callbacks to read data from the server instead of performing a full round trip.

20. Minimize the Use of Format()

When you can, use toString() instead of format(). In most cases, it will provide you with the functionality you need, with much less overhead.

21. Optimize Assignments

Use exp += val instead of exp = exp + val. Since exp can be arbitrarily complex, this can result in lots of unnecessary work. This forces the JIT to evaluate both copies of exp, and many times this is not needed. The first statement can be optimized far better than the second, since the JIT can avoid evaluating the exp twice.

22. Include Return Statements with in the Function

Explicitly using return allows the JIT to perform slightly more optimizations. Without a return statement, each function is given several local variables on stack to transparently support returning values without the keyword. Keeping these around makes it harder for the JIT to optimize, and can impact the performance of your code. Look through your functions and insert return as needed. It doesn't change the semantics of the code at all, and it can help you get more speed from your application

23. Use For Loops for String Iteration

The tradeoff for this generalization is speed, and if you rely heavily on string iteration you should use a For loop instead. Since strings are simple character arrays, they can be walked using much less overhead than other structures.

Foreach is far more readable, and in the future it will become as fast as a For loop for special cases like strings. Unless string manipulation is a real performance hog for you, the slightly messier code may not be worth it.

24.Precompiling pages and disabling AutoEventWireup

By precompiled pages, users do not have to experience the batch compile of your ASP.NET files; it will increase the performance that your users will experience.

Also setting the AutoEventWireup attribute to false in the Machine.config file means that the page will not match method names to events and hook them up (for example, Page_Load). If page developers want to use these events, they will need to override the methods in the base class (for example, they will need to override Page.OnLoad for the page load event instead of using a Page_Load method). If you disable AutoEventWireup, your pages will get a slight performance boost by leaving the event wiring to the page author instead of performing it automatically.

25. Use Jagged Arrays instead of rectangular Arrays

The v1 JIT optimizes jagged arrays (simply 'arrays-of-arrays') more efficiently than rectangular arrays, and the difference is quite noticeable. Here is a table demonstrating the performance gain resulting from using jagged arrays in place of rectangular ones in both C# and Visual Basic

26. Put Concatenations in One Expression

If you have multiple concatenations on multiple lines, try to stick them all on one expression. The compiler can optimize by modifying the string in place, providing a speed and memory boost. If the statements are split into multiple lines, the Visual Basic compiler will not generate the Microsoft Intermediate Language (MSIL) to allow in-place concatenation.

27. Avoid Unnecessary Indirection

When you use byRef, you pass pointers instead of the actual object. Many times this makes sense (side-effecting functions, for example), but you don't always need it. Passing pointers results in more indirection, which is slower than accessing a value that is on the stack. When you don't need to go through the heap, it is best to avoid it.

28. Use Charw

Use charw instead of char. The CLR uses Unicode internally, and char must be translated at run time if it is used. This can result in a substantial performance loss, and specifying that your characters are a full word long (using charw) eliminates this conversion.

29. Use Binary Compare for Text

When comparing text, use binary compare instead of text compare. At run time, the overhead is much lighter for binary.

30. Partial Classes (or Split classes)

Partial classes can improve code readability and maintainability by providing a powerful way to extend the behavior of a class and attach functionality to it.

One of the language enhancements in .NET 2.0-available to both VB2005 and C# 2.0 programmers-is support for partial classes. In a nutshell, partial classes mean that your class definition can be split into multiple physical files. Logically, partial classes do not make any difference to the compiler. During compile time, it simply groups all the various partial classes and treats them as a single entity.

One of the greatest benefits of partial classes is that they allow a clean separation of business logic and the user interface (in particular, the code that is generated by the Visual Studio Designer). Using partial classes, the UI code can be hidden from the developer, who usually has no need to access it anyway. Partial classes also make debugging easier, as the code is partitioned into separate files. This feature also helps members of large development teams work on their pieces of a project in separate physical files.

31. Use "array Lists" in place of arrays.

An ArrayList as everything that is good about an array PLUS automatic sizing, Add, Insert, Remove, Sort, BinarySearch. All these great helper methods are added when implementing the IList interface, the specifics of which are explored in the next section. The downside of an ArrayList is the need to cast objects upon retrieval.

32. Use "For each" Instead of For.

While writing this sample, we forgot to subtract one from people.Length. It was an immediately obvious mistake, but it could have been avoided by using

For Each.

When you use "For each" with an array, as you did here, the compiled Intermediate Language (IL) code is identical to the code you wrote as a For. Unless you require more complex behavior, such as iterating in reverse or iterating over every other item, always be sure to use For Each to iterate over arrays and most collections. The language-specific compiler handles this expansion and you reap the benefit. Your code will be less prone to off-by-one bugs, and it will be much easier to read.

33. Appropriate data type based on the requirement.

Use binary, int16, int32, int64 in place of integer according to the need..

In Database Operations

1. Return Multiple Resultsets

Using a single Data Reader we can execute multiple queries simultaneously.

http://www.ondotnet.com/pub/a/dotnet/2002/12/16/multiresultsets_1202.html?page=1

2. Paged Data Access through SP

3. Connection Pooling and Object Pooling

Connection pooling is a useful way to reuse connections for multiple requests, rather than paying the overhead of opening and closing a connection for each request. It's done implicitly, but you get one pool per unique connection string. If you're generating connection strings dynamically, make sure the strings are identical each time so pooling occurs. Also be aware that if delegation is occurring, you'll get one pool per user. There are a lot of options that you can set for the connection pool, and you can track the performance of the pool by using the Perfmon to keep track of things like response time, transactions/sec, etc.

4. Parameters while Inserting/Updating

5. Use SqlDataReader Instead of Dataset wherever it is possible

a. For retrieving large data from DB

b. Data with no relations.

6. Turn off Features You Don't Use

A pooled transactional object must enlist its connection into the current transaction manually. To enable it to do so, you must disable automatic transaction enlistment by setting the connection string Enlist property to False.

Turn off automatic transaction enlistment if it's not needed. For the SQL Managed Provider, it's done via the connection string:

SqlConnection conn = new SqlConnection("Server=mysrv01;Integrated Security=true; Enlist=false");

When filling a dataset with the data adapter, don't get primary key information if you don't have to (e.g. don't set MissingSchemaAction.Add with key):

public DataSet SelectSqlSrvRows(DataSet dataset,string connection,string query)

{

SqlConnection conn = new SqlConnection(connection);

SqlDataAdapter adapter = new SqlDataAdapter();

adapter.SelectCommand = new SqlCommand(query, conn);

adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;

adapter.Fill(dataset);

return dataset;

}

7. Keep Your Datasets Lean

Only put the records you need into the dataset. Remember that the dataset stores all of its data in memory, and that the more data you request, the longer it will take to transmit across the wire.

8. Use Sequential Access as Often as Possible

With a data reader, use CommandBehavior.SequentialAccess. This is essential for dealing with blob data types since it allows data to be read off of the wire in small chunks. While you can only work with one piece of the data at a time, the latency for loading a large data type disappears. If you don't need to work the whole object at once, using Sequential Access will give you much better performance.

9. CommandBehavior.CloseConnection

We don't need to specify explicitly something like close because we specified this in SqlCommand.ExecuteReader as CommandBehavior.CloseConnection. This option automatically closes the connection after we have finished with our work. Any exceptions thrown will be caught and displayed in the error message.

http://www.codeguru.com/vb/gen/vb_database/adonet/article.php/c5153/

10. Inefficient queries. Queries that process and then return more columns or rows than necessary waste processing cycles that could best be used for servicing other requests. Queries that do not take advantage of indexes may also cause poor performance.

11. Retrieving too much data. Too much data in your results is usually the result of inefficient queries. The SELECT * query often causes this problem. You do not usually need to return all the columns in a row. Also, analyze the WHERE clause in your queries to ensure that you are not returning too many rows. Try to make the WHERE clause as specific as possible to ensure that the least number of rows are returned.

12. Inefficient or missing indexes. Query efficiency decreases when indexes are missing because a full table scan must be performed. Also, as your data grows, tables may become fragmented. Failure to periodically rebuild indexes may also result in poor query performance.

13. Unnecessary round trips. Round trips significantly affect performance. They are subject to network latency and to downstream server latency. Many data-driven Web sites heavily access the database for every user request. While connection pooling helps, the increased network traffic and processing load on the database server can adversely affect performance. Keep round trips to an absolute minimum.

14. Too many open connections. Connections are an expensive and scarce resource, which should be shared between callers by using connection pooling. Opening a connection for each caller limits scalability. To ensure the efficient use of connection pooling, avoid keeping connections open and avoid varying connection strings.

15. Failure to release resources. Failing to release resources can prevent them from being reused efficiently. If you fail to close connections before the connections fall out of scope, they are not reclaimed until garbage collection occurs for the connection. Failing to release resources can cause serious resource pressure and lead to shortages and timeouts.

16. Transaction misuse. If you select the wrong type of transaction management, you may add latency to each operation. Additionally, if you keep transactions active for long periods of time, the active transactions may cause resource pressure. Transactions are necessary to ensure the integrity of your data, but you need to ensure that you use the appropriate type of transaction for the shortest duration possible and only where necessary.

17. Overnormalized tables. Overnormalized tables may require excessive joins for simple operations. These additional steps may significantly affect the performance and scalability of your application, especially as the number of users and requests increases.

18. Avoid Moving Binary Large Objects Repeatedly

Avoid moving BLOB data more than one time. For example, if you build a Web application that serves images, store the images on the file system and the file names in the database instead of storing the images as BLOBs in the database.

Storing the images as BLOBs in the database means that you must read the BLOB from the database to the Web server and then send the image from the Web server to the browser. Reading the file name from the database and having the Web server send the image to the browser reduces the load on the database server. It also reduces the data that is sent between the database and the Web server. This can significantly affect performance and scalability.

18. Use the ConnectionState property.

Avoid relying on an error handler to detect connection state availability. When you can, use the ConnectionState.Open or ConnectionState.Close method to check the state before use.

19. Reduce Serialization

Dataset serialization is more efficiently implemented in .NET Framework version 1.1 than in version 1.0. However, Dataset serialization often introduces performance bottlenecks. You can reduce the performance impact in a number of ways:

a. Use column name aliasing. The serialized data contains column names so that you can use column name aliasing to reduce the size of the serialized data.

b. Avoid serializing multiple versions of the same data. The DataSet maintains the original data along with the changed values. If you do not need to serialize new and old values, call AcceptChanges before you serialize a DataSet to reset the internal buffers.

c. Reduce the number of DataTable objects that are serialized. If you do not need to send all the DataTable objects contained in a DataSet, consider copying the DataTable objects you need to send into a separate DataSet.

20. Cancel Pending Data

When you call the Close method, the method does not return until all the remaining data has been fetched. If you know you have pending data when you want to close your DataReader, you can call the Cancel method before you call Close to tell the server to stop sending data.

This approach does not always result in a performance improvement, because Cancel is not guaranteed to make the server stop sending data. Control information is still exchanged after the call to Cancel, and the control information may or may not be interleaved with leftover data. Therefore, before you restructure your code to call Cancel before Close, test Cancel to learn if it actually helps in your particular scenario and to learn if you really need the extra performance at the expense of readability.

Note If you need output parameters, do not call Close until you have retrieved the output parameters. After you retrieve the output parameters, you can then call Close.

21. Consider SET NOCOUNT ON for SQL Server

When you use SET NOCOUNT ON, the message that indicates the number of rows that are affected by the T-SQL statement is not returned as part of the results. When you use SET NOCOUNT OFF, the count is returned. Using SET NOCOUNT ON can improve performance because network traffic can be reduced. SET NOCOUNT ON prevents SQL Server from sending the DONE_IN_PROC message for each statement in a stored procedure or batch of SQL statements.

For example, if you have eight operations in a stored procedure, eight messages are returned to the caller. Each message contains the number of rows affected by the respective statement. When you use SET NOCOUNT ON, you reduce the processing that SQL Server performs and the size of the response that is sent across the network.

Note: In Query Analyzer, the DONE_IN_PROC message is intercepted and displayed as "N rows affected.

22. Do Not Use CommandBuilder at Run Time

CommandBuilder objects such as SqlCommandBuilder and OleDbCommandBuilder automatically generate the InsertCommand, UpdateCommand, and DeleteCommand properties of a DataAdapter. The CommandBuilder objects generate these properties based on the SelectCommand property of the DataAdapter. CommandBuilder objects are useful when you are designing and prototyping your application. However, you should not use them in production applications. The processing required to generate the commands affects performance. Manually create stored procedures for your commands, or use the Visual Studio® .NET design-time wizard and customize them later if necessary.

23. Pool Connections

Creating database connections is expensive. You reduce overhead by pooling your database connections. Make sure you call Close or Dispose on a connection as soon as possible. When pooling is enabled, calling Close or Dispose returns the connection to the pool instead of closing the underlying database connection.

You must account for the following issues when pooling is part of your design:

a. Share connections. Use a per-application or per-group service account to connect to the database. This creates a single pool or a small number of pools, and it enables many client requests to share the same connections.

b. Avoid per-user logons to the database. Each logon creates a separate pooled connection. This means that you end up with a large number of small pools. If you need a different user for each connection, disable pooling or set a small maximum size for the pool.

c. Do not vary connection strings. Different connection strings generate different connection pools. For example, using different capitalization, extra spaces, or different ordering of attributes causes connections to go to different pools. The SQL Server .NET Data Provider performs a byte-by-byte comparison to determine whether connection strings match.

d. Release connections. Do not cache connections. For example, do not put them in session or application variables. Close connections as soon as you are finished with them. Busy connections are not pooled.

e. Passing connections. Do not pass connections between logical or physical application layers.

f. Consider tuning your pool size if needed. For example, in the case of the .NET Framework Data Provider for SQL Server, the default minimum pool size is zero and the maximum is 100. You might need to increase the minimum size to reduce warm-up time. You might need to increase the maximum size if your application needs more than 100 connections.

g. Connection pools are managed by the specific database provider. SqlClient, OleDB client, and third-party clients may provide different configuration and monitoring options.

The following list details the pooling mechanisms that are available, and it summarizes pooling behavior for the .NET Framework data providers:

h. The .NET Framework Data Provider for SQL Server pools connections by using a pooling mechanism implemented in managed code. You control pooling behaviors such as lifetime and pool size through connection string arguments.

i. The .NET Framework Data Provider for Oracle also pools connections by using a managed code solution.

j.The .NET Framework Data Provider for OLE DB automatically uses OLE DB session pooling to pool connections. You control pooling behavior through connection string arguments.

k. The .NET Framework Data Provider for ODBC uses ODBC connection pooling.

24. Do Not Explicitly Open a Connection if You Use Fill or Update for a Single Operation

If you perform a single Fill or Update operation, do not open the connection before you call the Fill method, because the DataAdapter automatically opens and closes the connection for you. The following code fragment shows how to call Fill.

The SqlDataAdapter automatically opens the connection, runs the selected command, and then closes the connection when it is finished. This enables the connection to be open for the shortest period of time.

Note that if you need to perform multiple file or update operations, you need to open the connection before the first Fill or Update method and close it after the last one. Alternatively, you could wrap multiple Fill or Update operations inside a C# using block to ensure that the connection is closed after the last use

25. Explicitly Close Connections

Explicitly call the Close or Dispose methods on SqlConnection objects as soon as you finish using them to release the resources that they use. Do not wait for the connection to fall out of scope. The connection is not returned to the pool until garbage collection occurs. This delays the reuse of the connection and negatively affects performance and scalability. The following are guidelines to consider. These guidelines are specific to SqlConnection because of the way it is implemented. These guidelines are not universal for all classes that have Close and Dispose functionality.

a. Using either the Close method or the Dispose method is sufficient. You do not have to call one method after the other. There is no benefit to calling one method after the other.

b. Dispose internally calls Close. In addition, Dispose clears the connection string.

c. If you do not call Dispose or Close, and if you do not use the using statement, you are reliant upon the finalization of the inner object to free the physical connection.

d. Use the using statement, instead of Dispose or Close, when you are working with a single type, and you are coding in Visual C#®. Dispose is automatically called for you when you use the using statement, even when an exception occurs.

e. If you do not use the using statement, close connections inside a finally block. Code in the finally block always runs, regardless of whether an exception occurs.

f. You do not have to set the SqlConnection reference to null or Nothing because there is no complex object graph. Setting object references to null or to Nothing is usually done to make a graph of objects unreachable.

Note: Closing a connection automatically closes any active DataReader objects that are associated with the connection.

26. Using the "using" statement

The using statement can be used to specify a boundary for the object outside of which, the object is destroyed automatically. The runtime invokes the Dispose method of the objects that are specified within this statement when the control comes out of this block. This is why this is a preferred choice when using exceptions for managing resources in .NET. Refer to the following code that uses the "using" statement:

string connectionString = ...; // Some connection string

using (SqlConnection sqlConnection = new SqlConnection(connectionString))

{

sqlConnection.Open();

//Some code

}

Note that when the end of the using block would be encountered, the Dispose () method will be immediately called on the instance. Note that when the Dispose() method is called on this connection instance, it checks to see if the connection is opened; if open it would close it implicitly prior to disposing off the instance.

27. The EnforceConstraints property of the dataset to false to turn off the constraints checking. Then use BeginLoadData and EndLoadData methods to turn off the index maintenance for faster processing in a dataset that needs to be populated from the database.

28. When you are no longer using an object it can be disposed, which is when the dispose method is called. When an object is disposed it should release any resources it is holding. I.e. closing database connections, destroying large structures it might be holding like a Data Table etc. The object itself is still in memory though and periodically .net will "garbage collect" which is when it removes all unused (ie disposed) objects from memory. It is this garbage collection that is when the finalize event is called, ie just before it is to be physically removed from memory.

Conclusion

I hope This article is useful for Beginers and Intermediate level Developers. I have covered most of the Performance tips. If any thing needed Please inform for further updations.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Suresh Alapati
Software Developer
India India
Working as a .Net Developer.

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GeneralThanks PinmemberAmolPandurangBorkar29-Dec-09 22:59 

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