I am running latest version of OpenGrok (opengrok-0.11.1), which is using ctags-5.8 to generate indexes for Mercurial repository.
After each OpenGrok index rebuild process, the temporary files generated by ctags are left in the temp directory (for example tags.P$&IRY).
Any idea why this would be the case?
I saw some exceptions during this process, which are suggesting some sort of issue with multithreading process probably initiated in OpenGrok.

at java.util.concurrent.Executor$RunnableAdapter.cal (Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(Futu reTask.java:303)
at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:736)