session hang for same row update

[AI Rumman <rummandba@xxxxxxxxx>]

Could anyone please tell me why the session 2 is hanging?

I am using Postgresql 9.1.

show deadlock_timeout ;

 deadlock_timeout 

------------------

 1s

(1 row)

  select * from t2;

 i | nam 

---+-----

 2 | t4

 1 | t3

Session 1:

BEGIN

update t2 set nam = 't3' where i=2;

UPDATE 1

Session 2:

BEGIN

update t2 set nam = 't3' where i=2;

hanged