mycat做读写分离，读写都分发到写服务器上，为毛啊？

Question

<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1">
</schema>
<dataNode name="dn1" dataHost="localhost1" database="test" />
<dataHost name="localhost1" maxCon="1000" minCon="10" balance="3"
          writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
    <heartbeat>show slave status</heartbeat>
    <!-- can have multi write hosts -->
    <writeHost host="hostM1" url="localhost:3306" user="root"
               password="">
        <!-- can have multi read hosts -->
        <readHost host="hostS2" url="localhost:3307" user="root" password="" />
    </writeHost>
    <!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> -->
</dataHost>