Is it essential to call shutdown() on HikariDataSource?

[timmolter]

No description provided.

[brettwooldridge]

shutdown() or close() is essential at application termination, otherwise you will leave database resources in use. Most IoC containers (Spring, JBoss, Hibernate, Tomcat) have a way to invoke a "destroy" method.

Somewhat riskier, but still workable, is to set minimumIdle connections to 0, set the actual database to timeout connections after, for example, 5 minutes, and set the idleTimeout and maxLifetime in HikariCP to 4 minutes. This way, if the application aborts "uncleanly", the database itself will terminate and cleanup the connections after 5 minutes.

Actually, even when minimumIdle is non-zero, is it not a bad idea to configure the native database timeouts to between 5-20 minutes, and the HikariCP maxLifetime about two minutes shorter than that. There will be little discernable impact on performance for your application, but you can actually avoid some memory leaks present in databases due to long-held connections.

[timmolter]

Thanks for the explanation. Very helpful.

What if I have DataSource ds = new HikariDataSource();. How would you recommend closing ds since DataSource does not have a close() method? I noticed HikariDataSource implements Closable, but I'm not sure if that helps in my case.

[brettwooldridge]

Closeable will help if you have raw DataSource and you are sure it is a HikariDataSource, you can simply cast to Closeable and call close (and possibly have to suppress a casting warning in your IDE).

Issue #208 just before this one, when fixed, will allow you to call ds.unwrap(HikariDataSource.class).close().

[timmolter]

Is it just me or is it odd that DataSource does not have a cleanup method? It seems like every DataSource impl needs to implement some clean up. My particular problem is that I don't know if the Datasource is a HikariDataSource or something else.

[brettwooldridge]

I agree, it is odd. It is even stranger that (at a minimum) the DataSource (or at least PooledDataSource), in Java 8 still does not implement Closeable. Would have been nice.

[sundhr]

When the OS takes care of cleaning up the resources when the process exits, why should I take care of closing it during termination of the program?