11 processes and their priority levels

process: The base of the operating system structure, the smallest unit of resource allocation.

thread: a thread exists in the process and is the smallest unit of operating system scheduling execution.

One operating system contains multiple processes, and one process contains multiple threads.

process in Android:

when a Android app launches and the system starts a process and a main thread to run the app. the Android system will do its best to keep the process stable and secure. However, in special cases, the old process is always removed to reclaim memory for new or more important processes. When you want to reclaim memory, the system decides which ones should be retained and which should be killed. Therefore, in Android Process Management, the priority level of the process is set. The priority depends on the program running within the process and the state of the program.

then when the system needs to reclaim memory, it is necessary to kill the low-priority process. This is the strategy of the Android system.

Mobile phones are used in different computer operating systems:

after the mobile phone is applied, the process is not destroyed; The used process is resident in memory;

five levels of priority:

1,Foreground process Common For example, the user is operating the interface

2, visisble process visible processes: Read the ebook, came a telephone, at this time the phone is visible process;

3, Service process: Common example: Side put music, you can put the ebook.

4, Background process: timing detection update;

5. Empty: null process, auxiliary process, cache process;

Note: The important level of the process may change at any time during operation.

11 processes and their priority levels