Common performance optimization methods in ASP. NET (1)

1. database access performance optimization
Database Connection and Shutdown
To access database resources, you need to create a connection, open a connection, and close the connection. These processes need to exchange information with the database multiple times for authentication, which consumes server resources. ASP. NET provides Connection Pool) to improve the impact of opening and closing databases on performance. The system places the user's database connection in the connection pool. If necessary, the connection is taken out. When the connection is closed, the connection is withdrawn and the next connection request is waited.

The size of the connection pool is limited. If you still need to create a connection after the connection pool reaches the maximum limit, the performance will be greatly affected. Therefore, after a database connection is established, the connection is enabled only when operations are required. The connection is closed immediately after use, so as to minimize the time for opening the database connection and avoid exceeding the connection limit.
Use stored procedures
Stored procedures are a set of pre-compiled SQL statements stored on the server, similar to the batch processing files in the DOS system. Stored Procedures provide the ability to access databases immediately and process information quickly. Using the stored procedure can avoid multiple compilation of commands. After one execution, the execution plan will reside in the cache. In the future, you only need to directly call the binary code in the cache.
In addition, the stored procedure runs on the server and is independent from the ASP. NET program to facilitate modification. The most important thing is that it can reduce the transmission of database operation statements over the network.
Optimize Query statements
In ASP. NET, the ADO connection consumes a considerable amount of resources. The longer the SQL statement runs, the longer the system resources are occupied. Therefore, try to use optimized SQL statements to reduce execution time. For example, a query statement that does not contain a subquery statement makes full use of indexes.
2. Optimized string operation performance
Use the ToString method of the Value Type
When connecting strings, you often use the "+" sign to directly add numbers to strings. This method is simple and can get the correct results. However, because different data types are involved, the numbers must be converted to the reference type through the boxing operation before they can be added to the string. However, the packing operation has a great impact on the performance, because during such processing, a new object will be allocated in the managed heap, and the original value will be copied to the newly created object.
The Value Type ToString method can be used to avoid packing and improve application performance.
Use StringBuilder class
The String class object cannot be changed. In essence, the re-assignment of the String object re-creates a String object and assigns the new value to the object, the ToString method does not significantly improve the performance.
When processing strings, it is best to use the StringBuilder class. Its. NET namespace is System. Text. This class does not create a new object, but directly performs operations on strings through Append, Remove, Insert, and other methods, and returns the operation results through the ToString method.
Its definition and operation statement are as follows:
Int num;
System. Text. StringBuilder str = new System. Text. StringBuilder (); // create a string
Str. Append (num. ToString (); // Add the numeric value num
Response. Write (str. ToString); // display the operation result

3. Optimize configuration files for Web server computers and specific applications to meet your specific needs
By default, ASP. NET configuration is set to enable the widest range of features and adapt to the most common solutions. Therefore, application developers can optimize and modify some of the configurations based on the features used by the application to improve application performance. The following lists some options you should consider.
Only enable authentication for the desired application. By default, the authentication mode is Windows, or NTLM is integrated. In most cases, it is best to disable authentication in the Machine. config file and enable authentication in the Web. config file for applications that require authentication.
Configure the application based on the appropriate request and response encoding settings. ASP. NET default encoding format is UTF-8. If your application is strictly ASCII, configure the application to use ASCII for a slight performance improvement.

Disable AutoEventWireup for applications. In the Machine. config file, set the AutoEventWireup attribute to false, which means that the page does not match the method name and event or hook the two, for example, Page_Load ). If Page developers want to use these events, they need to rewrite these methods in the base class. For example, they need to rewrite Page. OnLoad for Page loading events, rather than using Page_Load ). If AutoEventWireup is disabled, the page will be slightly improved by leaving the event connection to the page author rather than automatically executing it.
Remove unused modules from the request processing pipeline. By default, all functions of the For example, if you do not use session Status and output cache in an application, you can remove them from the 4. Disable the debugging mode.
Remember to Disable debug mode before deploying production applications or performing any performance measurements. If the debug mode is enabled, the performance of the application may be greatly affected.

5. For applications that rely heavily on external resources, consider enabling network gardening on a multi-processor computer.
ASP. NET process model helps enable scalability on a multi-processor computer and distribute work to multiple processes, each with one CPU), and each process sets the processor relationship to its CPU. This technology is called Web gardening. If the application uses a slow database server or calls a COM Object with external dependencies, it only mentions two possibilities), it is helpful to enable Network gardening for your application. However, before deciding to enable Web gardening, you should test how applications are executed in the Web garden.
6. cache data and page output whenever possible
ASP. NET provides some simple mechanisms to cache the output or data of these pages when you do not need to request dynamic computing page output or data for each page. In addition, you can optimize the performance of pages and data requests to be cached, especially in areas where the site is expected to have a large amount of communication. Compared with any Web form function of. NET Framework, using the cache appropriately can improve the performance of the website. Sometimes this increase is more than an order of magnitude.

There are two points to note when using the ASP. NET cache mechanism. First, do not cache too many items. Each item in the cache has an overhead, especially for memory usage. Do not cache items that are easy to recalculate and rarely used. Second, the period of validity allocated to cached items should not be too short. Items that expire soon will result in unnecessary turnover in the cache, and often lead to more code cleanup and garbage collection work. If you are concerned about this issue, monitor the Cache Total Turnover Rate performance counters associated with ASP. NET Applications performance objects. High turnover rate may indicate problems, especially when items are removed before expiration. This is also called memory pressure.
7. Select a data view mechanism suitable for pages or applications
There are often important trade-offs between convenience and performance based on how you choose to display data on a Web form page. For example, the DataGrid Web server control may be a convenient and quick way to display data, but its overhead is often the largest in terms of performance. In some simple cases, it may be very effective to generate an appropriate HTML to present your own data, but custom and browser targeting will quickly offset the extra benefits you get. The Repeater Web Server Control is a compromise between convenience and performance. It is efficient, customizable, and programmable.
8. Use the SqlDataReader class for fast data-only cursor
The SqlDataReader class provides a method for reading data streams only retrieved from the SQL Server database. If you are allowed to use an ASP. NET application when creating it, The SqlDataReader class provides higher performance than the DataSet class. This is because SqlDataReader uses the Local Network Data Transmission Format of SQL Server to directly read data from the database connection. In addition, the SqlDataReader class implements the IEnumerable interface, which allows you to bind data to server controls. For more information, see SqlDataReader class. For information about how ASP. NET accesses data, see access data through ASP. NET.
9. Use SQL Server Stored Procedures for data access
Among all data access methods provided by. NET Framework, SQL Server-based data access is a recommended choice for generating high-performance, scalable Web applications. When using a hosted SQL Server Provider, you can use compiled stored procedures instead of special queries to obtain additional performance improvements.