Alter table command for renaming table is getting stuck.

Hi, I am working on a data warehousing project, our system is handling
huge amount of live data.
We get data in form of events.
Frequency of events goes up to 1000 events/second. average frequency is 200
events/second.
We are using libpg to connect pg-server and insert each event into database
tables.
As a part of data warehousing I am rotating table every 50000 records.
Also to reduce overhead I commit a transaction after inserting 1000 records.

Problem I am facing is as follows

While rotating (renaming) a table the "alter table" command is stuck and
whole system is blocked.
Blocking is also observed while "creating new table" after rename command is
finished.

No other process/query is accessing this table until rotation is done.

The problem occurs twice a day, rest of the time it is working fine.
I could not find the cause.

Please give me suggestions / solution

Thanks in advance.

--
Dhaval.