Sidekiq kills in between without any reason server RAM is approx 8GB

I am working on the Ruby on rails application, my workers are running on the sidekiq-6.0.1. generally I'm using this to send the push notifications on android and ios devices etc.

I'm running sidekiq in the background using the following command:

bundle exec sidekiq -L log/sidekiq.log -C config/sidekiq.yml -e development &

Sidekiq runs in background successfully but after a couple of hours or sometimes in a couple of minutes kills silently.

There is not any memory issue, My server RAM is 8 GB.

Please help me to get a best way to deal with this case.