具有单个应用程序服务器实例的数据库连接池

Question

I am connecting to a remote MySQL database in my node.js server code for a web app. Is there any advantage to using a connection pool when I only have a single instance of a node.js application server running?

Answer 1

Connection pools are per instance of application. When you connect to the db, you are doing it from that particular instance and hence the pool is in the scope of that instance. The advantage of creating a pool is that you don't create / close connections very often, as this is, in general, a very expensive process. Rather, you maintain a set of connections open, in idle state, ready to be used if there is a need.

Update

In node there is async.parallel() construct which allows you to launch a set of tasks in async manner. Immagine that those tasks represent each one a single query. If you have a single connection to use, each process should use that same one, and it will quickly become a bottelneck. Instead, if you have a pool of available connections, each task can use a separate connection until the pool is completely used. Check this for more detailed reference.