[ros-users] Subscriber messages Queue

Hi Friends.
I am using Rosjava and observed something.

In subscriber side, I have done a sleep of 10 sec.
I observed tahat after 10 second when subscriber wakes up and gets new
notification, that notification is for message which was published 10 sec
before.
It looks like message are getting queued up for that subscriber.

Is that Expected behaviour? if subsciber is blocked for ever is there can be
a possibility of ouf memory?
I tried to make it outofMemory but it didnt happen.

Any expert comments?

Thanks and Regards
Abhishek Verma