A system was found to have exhausted all (50) database connections and failed to recover. Inspection of the thread dump revealed 49 threads with the following trace:

The line with “org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation” shows that a DB connection has already been acquired and a transaction has been started. Later “org.opennms.netmgt.filter.JdbcFilterDao.getNodeMap(JdbcFilterDao.java:173)” tries to acquire another connection on the same thread without releasing the prior connection, leaving these calls prone to deadlocks. This is caused by mixing Spring AOP managed transactions w/ direct manipulation of JDBC calls.