fix dastimestamp message
remove debug printout
Use connection alive function instead of performing a call to retrieve database names
Add lock to cleanup_worker to prevent race conditions between clena-up and request processing; add fsync while update das record with ok status; remove clean-up of expired record from remove_expire since it creates race conditions
Enhance update_das_query function to cover syncdelay of MongoDB; match db record status with provided one and improve printout message and delay interval