50 concurrent supports 50 users. According to the relevant information of the query, 50 concurrent users can only connect to the database of 50 users at the same time. Sharing means more users. The concurrency of the database is limited, and it cannot accommodate tens of thousands of concurrent connections at the same time. The connection pool must be loaded in the program, and the system maintains the number of connections through the connection pool. When browsing a web page, the server will establish a link with the browser of the viewer, and each link represents a concurrency. When a page contains many pictures, the pictures will not be displayed one by one.