wtf is hikaricp?

HikariCP is a JDBC connection pool for Java applications. A connection pool is a behind-the-scenes pool of pre-opened database connections that an application can borrow from and return to, so it does not pay the cost of opening a fresh connection every time it talks to the database. HikariCP's pitch is that it is fast, small, and reliable, the README calls it a zero-overhead, production-ready pool weighing in at roughly 90 kilobytes, and quotes Edsger Dijkstra's line that simplicity is a prerequisite for reliability. In practice you add HikariCP as a Maven dependency in your Java project, point it at your database, and let it manage connections for you. The library exposes a fairly small set of configuration knobs: an essential property to identify the JDBC DataSource class or a JDBC URL, plus username and password, and then optional settings like autoCommit, connectionTimeout (how long a caller will wait for a free connection), idleTimeout (how long an unused connection can sit before being closed), maximum pool size, and so on. HikariCP ships with sensible defaults, so for many applications you barely need to configure it. The author has also done extensive performance work using the OpenJDK JMH microbenchmark framework, and the README includes JMH benchmark results comparing HikariCP against other pools such as commons-dbcp2, Tomcat's pool, Vibur, and c3p0 on Java 8. There is also a separate Java 6 artifact for legacy applications, which is in maintenance mode. Someone would use HikariCP as the connection pool inside a Java service that talks to a relational database, web backends, batch jobs, or any application where the cost and reliability of database connections matter.