HikariCP

public Database() {
    try {
        Class.forName("org.mariadb.jdbc.Driver");
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }

    HikariConfig config = new HikariConfig();
    config.setJdbcUrl(App.getConfig().getString("database.url"));
    config.setUsername(App.getConfig().getString("database.user"));
    config.setPassword(App.getConfig().getString("database.pass"));
    config.addDataSourceProperty("cachePrepStmts", "true");
    config.addDataSourceProperty("prepStmtCacheSize", "250");
    config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
    config.addDataSourceProperty("allowMultiQueries", "true");
    config.setMaximumPoolSize(200); // this is plenty, the websocket uses 32
    HikariDataSource ds = new HikariDataSource(config);
}

References

• HikariCP connection pool
• Configuring a Hikari Connection Pool
• Java Code Examples for HikariDataSource
• How to configure datasource with HikariCP