Hi Pranav,
Sorry for the delayed reply, I've been away for a couple of days.
I suspect this is something to do with the Raspberry PI causing problems.
Have a read of these, this is all I could find;
Also try running FS with a completely fresh config, to rule out any strange configuration problems.
If you are still able to reproduce this problem then best thing to do would be to create a JIRA for this issue, one of the core devs would then give you some instructions on how to debug this further (as I'm not too sure how to enable debugging for thread failures).
See here for instructions on reporting to JIRA;
Hope this helps
Cal