Juozas wrote: > It is very dificult to find pooling > related bugs in application. May be > it has meaning to implement something > like "DebugPool" to help find problems > in users code. I can think about this, > if this idea is interesting.
In the pool/dbcp implementation from which commons-pool/commons-dbcp is derived, probably the most useful diagnostic we found, especially for the kinds of problems Glenn seems to be having, is to track the number of connections being used by each thread (using a ThreadLocal variable), and logging or throwing an exception when that number is greater than 1. In all cases I can think of when a thread is borrowing more than one connection from the same pool (or from mutliple pools) it is either a logic or design error. We ripped out that, and some logging, out of concern for the general case, but I like the idea of a DebugPool. Perhaps DebugPool could simply be a thin wrapper around an arbitrary pool, adding logging and related debugging calls.
