This occurred in the 24h max file test with FTPS.

The consequence is that the purging of cached published files occasionally fails. The purpose of the purging is to release memory.

This is clearly a threading issue.

Stack print printout:
ubuntu@excl-fronrunner-stability-bm:~/integration/test/mocks/datafilecollector-testharness/auto-test$ grep ERR logs/MaxFiles1MB_FTPS_24h/END_application.log
org.springframework.scheduling.support.TaskUtils$LoggingErrorHandler |2019-05-30T01:34:44.821Z |ERROR |Unexpected error occurred in scheduled task. |RequestID=9e7d0ee2-ab5b-4c4c-a36d-0eb60636cd3a |java.util.ConcurrentModificationException: null\n\tat java.util.HashMap$HashIterator.nextNode(HashMap.java:1445)\n\tat java.util.HashMap$EntryIterator.next(HashMap.java:1479)\n\tat java.util.HashMap$EntryIterator.next(HashMap.java:1477)\n\tat org.onap.dcaegen2.collectors.datafile.service.PublishedFileCache.purge(PublishedFileCache.java:59)\n\tat org.onap.dcaegen2.collectors.datafile.tasks.ScheduledTasks.purgeCachedInformation(ScheduledTasks.java:137)\n\tat org.onap.dcaegen2.collectors.datafile.configuration.SchedulerConfig.lambda$tryToStartTask$1(SchedulerConfig.java:109)\n\tat org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)\n\tat java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)\n\tat java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)\n\tat java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)\n\tat java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)\n\tat java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)\n\tat java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)\n\tat java.lang.Thread.run(Thread.java:748)\n | |pool-2-thread-1 |