There was some issue with BackgrounDRb like Memory leakage, so it was braeking the cron jobs. There are alternatives to BackgrounDRb as Craken. Craken is best.
Craken is a Ruby on Rails plugin for managing and installing rake-centric crontab.
Craken Installation as,
./script/plugin install git://github.com/latimes/craken.git
Craken Configuration with Ruby on Rails app,
You need to write the RAKE task which needs to run after some intervals.
Suppose I have a RAKE task db:send_emails
Create Crontab file at following path,
#{RAILS_ROOT}/config/craken/raketab.yml
Add configuration to raketab.yml as,
my_config:
hour: 0
minute: *
day: *
month: *
command: db:send_emails > /tmp/db_send_emails.log 2>&1
Above configuration will run the “db:send_emails” tasks after very 24 hours (midnight)
Finally create the CRON job with following command,
rake craken:install
Above command will create a cronjob.
For Production mode,
rake craken:install RAILS_ENV=production
You are done 
More about it……..,
If we need to check the Cronjob, you can give the following command,
crontab -l
Following command displays the log once CRON job executes
tail -f /var/log/syslog
Ref URL – http://github.com/latimes/craken
