Yes I can confirm the same. If the DB goes down while the Quartz scheduler instance is running, the QuartzSchedulerThread goes wild trying to get a new connection repeatedly (as fast as it can), easily able to fully utilize 1 CPU core by doing just that.
It's exactly the same situation as described by schmidma above, with the most important part of the stack trace of the affected thread being (Quartz 2.2.1):
Code:
at org.quartz.utils.DBConnectionManager.getConnection(DBConnectionManager.java:108)
at org.quartz.impl.jdbcjobstore.JobStoreCMT.getNonManagedTXConnection(JobStoreCMT.java:165)
at org.quartz.impl.jdbcjobstore.JobStoreSupport.executeInNonManagedTXLock(JobStoreSupport.java:3784)
at org.quartz.impl.jdbcjobstore.JobStoreSupport.acquireNextTriggers(JobStoreSupport.java:2756)
at org.quartz.core.QuartzSchedulerThread.run(QuartzSchedulerThread.java:272)