At a customer site, collectd is occasionally failing to continue collecting values from some nodes. The symptom is a blank graph that remains blank until OpenNMS is restarted.
In the collectd.log file on this system, there are several exceptions being thrown. One is a ConcurrentModificationException that appears to be due to an active collection and Collectd's event listener accessing the scheduled outage configuration inside PollOutagesConfigManager at the same time. We need to fix this because it is a possible souce of the data collection failures.