On 03/12/2013 09:19 AM, Kevin Wooten wrote:
* Asynchronous I/O engine provided by Netty
* All connections share a single group of worker threads
That's going to cause serious issues on Java EE, especially when unloading applications. Since you're on JDBC4 you can have init and cleanup functions to manage the thread pool, but these are vital. I asked about this re PgJDBC quite some time ago and got some good information that's summarized here:
http://stackoverflow.com/q/8514725/398670 Failure to properly shut the thread pool down when a servlet or application is unloaded will cause classloader leaks, tending to lead to PermGenSpace exhaustion errors and other problems. The driver will probably need application-server-specific integration hooks too.
As for the "multiple JARs" converns, it's trivial to bundle dependencies inside the JDBC driver jar. However, this can cause issues if there's an incompatible version of the same library elsewhere on the classpath. It's OK if you're on a modern application server like JBoss AS 7 that isolates classloader chains, but it can be a real problem on older platforms and standalone applications. For this reason both a rollup version of the jar and a version without bundled libraries would probably be needed, but this is trivial to produce from Maven.
Overall I think this is an intriguing idea, whether it proves to be an ideas testbed or something that becomes appealing to adopt more seriously. Congratulations on tackling it.
-- Craig Ringer http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
