how can we resolving locking state....

hi..

we test   locking      PostgreSQL 8.4.4 on x86_64.

1> session 1
###########################
$ psql mydb
drop table citytest;
CREATE TABLE citytest (
       i_id integer ,
       city              varchar(80)
) ;
ALTER TABLE citytest ADD CONSTRAINT citytest_pkey PRIMARY KEY (i_id);

insert into citytest values (1,'aaa');
insert into citytest values (2,'bbb');

begin;
delete from citytest;
     <------- no commit/rollback
     <------- this will be Blocker

2> session 2,3,4
###########################
$ psql mydb
delete from citytest;
  <--- waiting 
  <--- these are  blocked....

3> os process
###########################
we just    kill   Blocker process    for  resolving  locking....
  but,   the other process   also    disappear ...

$ ps -ef| grep postgres
post1     4921     1  .. /u01/post1/bin/postgres -D /u02/post1data
post1     4924  4921  .. postgres: writer process                
post1     4925  4921  .. postgres: wal writer process            
post1     4926  4921  .. postgres: autovacuum launcher process   
post1     4927  4921  .. postgres: archiver process              
post1     4928  4921  .. postgres: stats collector process       
post1     5143  4921  .. postgres: post1 mydb [local] idle in transaction    <### Blocker
post1     5591  4921  .. postgres: post1 mydb 127.0.0.1(33982) DELETE waiting <### blocking
post1     5592  4921  .. postgres: post1 mydb 127.0.0.1(33983) DELETE waiting <### blocking
post1     5593  4921  .. postgres: post1 mydb 127.0.0.1(33984) DELETE waiting <### blocking
post1     5738   329  .. grep postgres
$
$   kill -9   5143
$
$ ps -ef| grep postgres
post1     4921     1  0 17:35 pts/2    00:00:00 /u01/post1/bin/postgres -D /u02/post1data
post1    10905  4921  0 17:39 ?        00:00:00 postgres: writer process                
post1    10906  4921  0 17:39 ?        00:00:00 postgres: wal writer process            
post1    10907  4921  0 17:39 ?        00:00:00 postgres: autovacuum launcher process   
post1    10908  4921  0 17:39 ?        00:00:00 postgres: archiver process              
post1    10909  4921  0 17:39 ?        00:00:00 postgres: stats collector process       
post1    10989   329  0 17:39 pts/2    00:00:00 grep postgres
$

Could you teach me,    Is this  expected  behavior ??  (disapper blocking process not only Blocker process)
and
Could you teach me,  how can we  eliminate  just  Blocker session...

Thanks....