Hi Kenn Takara
My value for wsrep_slave_threads is 8 and nproc show 16.
Here is my config for wsrep :
[mysqld]
wsrep_provider=/usr/lib64/galera3/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.1.20,192.168.1.21,192.168.1.23
binlog_format=ROW
# MyISAM storage engine has only experimental support
default_storage_engine=InnoDB
# Slave thread to use
wsrep_slave_threads= 8
wsrep_log_conflicts
# This changes how InnoDB autoincrement locks are managed and is a requirement for Galera
innodb_autoinc_lock_mode=2
# Node IP address
wsrep_node_address=192.168.1.23
# Cluster name
wsrep_cluster_name='OmniCluster'
#If wsrep_node_name is not specified, then system hostname will be used
wsrep_node_name=percona-node4
#pxc_strict_mode allowed values: DISABLED,PERMISSIVE,ENFORCING,MASTER
pxc_strict_mode=ENFORCING
# SST method
wsrep_sst_method=xtrabackup-v2
wsrep_sst_auth="xxx"