Baidu test preparation 1

Labels: how to use the window design program for data management database in windows?

I. Principles and conditions for database and thread deadlocks, and how to avoid deadlocks

1. The main causes of deadlocks are,

(1) Insufficient system resources

(2) The order in which processes run is not appropriate

(3) improper resource allocation

2. Four Conditions for deadlock

(1) mutex condition: A resource can only be used by one process at a time.

(2) request and retention conditions: when a process is blocked by requesting resources, it will not release the obtained resources.

(3) conditions of unavailability: resources obtained by a process cannot be forcibly deprived before they are used up.

(4) Cyclic waiting condition: if a process forms a cyclic waiting resource relationship that connects the beginning, end, and end

3. How to avoid deadlocks: destroy one of the four necessary conditions

II. List the three basic elements and five main design principles of object-oriented design.

1. three basic elements: inheritance, encapsulation, and Polymorphism

2. Main design principles: single responsibility principle, open-closed principle, interface isolation principle, dependency inversion principle, Rishi replacement principle, And Demeter principle.

3. Several methods and advantages and disadvantages of Windows Memory Management

Windows Memory Management methods include Page Management, segment management, and segment Page Management.

1. Page Management: Paging the memory without external fragments. The size of the internal fragments does not exceed the page size. Disadvantages increase machine costs and system overhead.

2. segment management: it is advantageous to segment programs by content or process functions. You can write and compile them separately, and use different treasures for different segments. Disadvantage: fragments are generated.

3. segment-and-Page Management: combines the above two methods to segment programs and store them by page. The advantages of the above two methods are as follows: disadvantages, complexity and overhead increase, speed down

Baidu test preparation 1