Subject Invalid connection after JBoss IdleRemover-Action (NPE)
Author Josef Gschwendtner

one of our customers is getting sporadically NullPointerExceptions
(which last for a certain period).

To avoid the great number of NPE's we have changed methode
isc_start_transaction in Jaybird to log a message on db.out == null and
throw an exception afterwards. This has improved the situation because
instead of many NPE's we get one exception and afterwards the program
works as expected, again.

One of our customers had this fault-situation (db.out == null) 5 times
last week. We found out, that the situation always occures immediately
after the JBoss IdleRemover-thread was active and probably has freed a
connection which was used by another thread (also the situation occures
not each time the IdleRemover-thread was active).
We think there might be a synchronisation problem.

Another customer runs the same program without any problems.
Both custumers use RedHat 7.2.
- Customer with problems uses kernel 2.4.20-28 (the newer one)
- Customer without problems uses kernel 2.4.7-108

Other Conditions:
- Software: Java 1.4.2_03, JBoss 3.2.3, Jaybird 1.5.5
- Hardware: Dual Xeon CPU (3,06 GHz), 2 GB RAM

Any help would be greatly appreciated.
Josef Gschwendtner