MariaDB Galera Cluster Memory Usage growing

I'm evaluating MariaDB cluster and I see massive grow in memory usage compared to Standalone MariaDB installation. Cluster tests are done in 3 Node envinronment. With Centos 6.1 and 1GB RAM. Basically replication is working fine between these nodes, but memory usage grows all the time without releasing it which makes it kinda unusable.

3 Node cluster Setup running following packages
MariaDB-server-5.5.25-1.x86_64
MariaDB-compat-5.5.25-1.x86_64
MariaDB-common-5.5.25-1.x86_64
MariaDB-client-5.5.25-1.x86_64

Node 1 my.cnf:

[mysqld]
server_id=1
datadir=/var/lib/mysql
user=mysql
log-bin=mysql-bin
log_slave_updates = 1
binlog_format=ROW
default_storage_engine=InnoDB
max_allowed_packet = 100M

wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address=gcomm://
wsrep_slave_threads=2
wsrep_cluster_name=mycluster
wsrep_sst_method=rsync
wsrep_node_name=node1
wsrep_replicate_myisam=1

innodb_locks_unsafe_for_binlog=1
innodb_autoinc_lock_mode=2
innodb_buffer_pool_size = 8M
innodb_additional_mem_pool_size = 4M
innodb_log_file_size = 64M
innodb_log_buffer_size = 8M
innodb_flush_method = O_DIRECT
innodb_flush_log_at_trx_commit = 1

Node 2/3 has identical my.cnf except wsrep_node_name and wsrep_cluster_address parameters.

create database ptest;
use ptest;
create table ti2(c1 int auto_increment primary key, c2 char(255)) engine=InnoDB;
insert into ti2(c2) values('abc');
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;
insert into ti2(c2) select c2 from ti2;

node1

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7133 mysql 20 0 1174m 104m 7548 S 0.0 10.5 0:00.12 mysqld

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7133 mysql 20 0 1943m 676m 18m S 0.7 67.8 0:59.21 mysqld

Nodes 2 and 3 has almost same memory usage so eventually all nodes will run out memory if inserts are continued.

Executing same test with standalone MariaDB with same InnoDB settings keeps memory as low as 116M.

STANDALONE MARIADB

MariaDB-common-5.5.28-1.x86_64
MariaDB-client-5.5.28-1.x86_64
MariaDB-server-5.5.28-1.x86_64
MariaDB-compat-5.5.28-1.x86_64

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2333 mysql 20 0 786m 72m 6028 S 0.0 7.3 0:00.24 mysqld

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2333 mysql 20 0 786m 116m 6960 S 0.0 11.7 0:33.72 mysqld

What could be causing this ? MariaDB cluster guide states are memory usage should increase only slightly compared to standalone installation.