IIS6.0 Web Park-The maximum number of working processes

IIS 6.0 allows the application pool to be configured as a Web garden. To understand the concept of a Web garden, imagine a scenario where you have an IIS 5.0 server and three Web sites, each Web site running the same application, and if IIS 5.0 can automatically follow a circular loop pattern to send requests sequentially to these functionally equivalent, In fact, separate Web sites, separating the load into three different processes, can form a small Web farm-the Web garden.

In the Web garden of IIS 6.0, we do not have to create additional Web sites, as long as you specify the number of worker processes to use for an application pool. The specific configuration steps are to open the Properties dialog box for the application pool, go to the Performance page, and enter the number of processes in the maximum worker processes input box under Web Garden, as shown in Figure eight. When the server load is small and no additional worker processes are required, IIS 6.0 automatically shrinks the actual number of worker processes after a certain amount of time (the default is 20 minutes, configurable), and if the load becomes larger, additional worker processes are required, and IIS 6.0 increases the number of worker processes again. All of this is done automatically and does not require administrator intervention.
Web garden: In the Web garden You can configure the maximum number of worker processes used by this application pool, default is 1, the maximum can be set to 4000000, configuration using multiple worker processes can improve the performance of the application pool processing requests, but before you set up to use multiple worker processes, consider the following two points:

Each worker process consumes system resources and CPU usage, and too many worker processes can lead to a sharp depletion of system resources and CPU utilization;

Each worker process has its own state data, and if the Web application relies on the worker process to save state data, it may not support the use of multiple worker processes.

Q: IIS 6.0 has a new feature called Web Garden, which allows you to configure an application pool to use multiple worker processes. When IIS creates additional worker processes. What we should know before we implement the Web park.

A: When you create an application pool, IIS 6 is notified to create a worker process to transfer the contents of the Web sites, files, and folders that are assigned to the application pool. You can configure the application pool to start multiple, not a worker process, which can improve scalability. This feature, called Web Park, is a small "Web farm". Instead of having to use multiple computers to deliver the same content (Web farm), you can use multiple processes on a single computer to deliver the same content.

When you configure an IIS 6 application as a Web garden, you only need to set a number of worker processes greater than 1 in the maximum number of worker processes box in the Performance tab of the application pool properties. If this value is greater than 1, each request will start a new worker process instance, and the maximum number of processes that can be started is the max worker process you specified. Subsequent requests are sent to the worker process in a circular manner.

Web parks are useful in situations where your application resources are limited. For example, if you have a slow connection to a database, you can use multiple worker processes to increase user throughput, increasing the number of connections to the database.

While it is useful to use the Web garden in some cases, it is important to note that the session information is unique for each worker process. Because requests are routed in a circular manner to the application pool worker process, the Web garden may not be very useful for the applications that the session information stores in the process. In a few cases, having multiple worker processes running the same application can cause resource contention. For example, if all worker processes are trying to log information to a journal file, or if they are using resources that are not dedicated to multiple concurrent accesses, there is a risk of resource contention.

If these problems do not exist, then the Web garden may be one of the features you need, and it can be very useful.