How is the application pool suddenly closed?

How to Apply Program The pool is suddenly closed.
Internet Information Service (IIS) Manager-> application pool-> defaultapppool-> right-click Properties
I. Recycling
1. Recycle schedule (minutes): Selected; Value: 1740
2. Reclaim the Working Process (number of requests): No (originally set to 35000)
3. Reclaim the working process at the following time: do not fill in
4. Process recycling when too much memory is consumed: all are not selected. (Items 2, 3, and 4 may avoid server response problems that may be caused by the forced recycle process when the traffic is high, leading to false IIS response failure)
Ii. Performance
Only idle timeout for 20 minutes is selected. None of them. The maximum number of worker processes in the Web garden is 1 (default ). Note that the Web Garden must be kept by default. If you enter other numbers greater than 1, the background programs of some website programs cannot be opened or refresh continuously.

The original request queue is limited to 4000, But not limited now.
Iii. Running status
The first two items are used by default. The startup time is limited to 90 seconds, and the shutdown time is limited to 180 seconds.

Remove the hook for enabling the quick failure protection!
In order to avoid having to ignore the prompt when many errors are encountered, you can just increase the protection scope of quick protection. For example, if the failure occurs for 50 times for five minutes, you can close the corresponding program.

The "Closing time limit is 180 seconds" is required. Because the process closing time is originally 90 seconds, it is a default value. If the process closing time exceeds 90 seconds, it is deemed to have timed out, this error occurs when the process shutdown time exceeds the limit log. Therefore, extend the time to avoid this error.

2nd methods:

Cause: the memory heap quota of independent processes is exhausted, and IIS cannot create more process workspaces for processing.

Solution:
1. HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ W3SVC
2. Create a New DWORD under the Parameters key. The name is usesharedwpdesktop and the value is 1. Restart IIS.

3rd types

The problem has been solved and the database connection cannot be released. I don't know why.CodeIt is good to be local, there is a problem on the server side, and finally add the following statement in the connection string to solve the problem.

Pooling = true; Max pool size = 512; min pool size = 50; connection lifetime = 30

4th types

Create an application pool. different websites reference different application pools.