Rails private_pub Issue with publish_to from controller

I am having strange behavior of faye when I publish message from controller. It doesn't send message to 100% of channels subscribed. I mean if I open 20 tabs and send a message, the message does not always publish on all 20 tabs, instead it misses out some tabs.

I am using private pub gem version 1.0.3 I am using heroku app as faye server for implementation. Please help.