When to use singleton pattern?

Single case mode is a commonly used software design pattern. When applying this pattern, the class of a singleton object must ensure that only one instance exists. Many times the entire system only needs to have one global object, which helps us coordinate the overall behavior of the system. For example, in a server program, the server's configuration information is stored in a file. These configuration data are uniformly read by a singleton object, and then other objects in the service process obtain the configuration information through this singleton object. This approach simplifies configuration management in complex environments.

#The singleton mode only allows the creation of one object, which can save memory and speed up object access. Therefore, the singleton pattern is suitable for use when objects need to be shared.

Such as:

1. Objects that need to be instantiated and then destroyed frequently.
2. Objects that take too much time to create or consume too many resources, but are frequently used.
3. Stateful tool object.
4. Objects that frequently access databases or files.

Classic usage scenarios:
1. In the case of resource sharing, avoid performance or loss caused by resource operations. As in the log file above, apply the configuration.
2. When resources are controlled, it facilitates communication between resources. Such as thread pool, etc.

Related tutorials: Design pattern video tutorial

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