Query statements with 2 subqueries can cause thread insecurities

[FlyingMao]

• dble version：
  5.6.1-dble-9.9.9.9-61be3b260ee1a279e672e56805508c3cd115a639-20190102095816
• preconditions ：

drop table if exists test_shard;
create table test_shard (id int(11) primary key,R_bit bit(64),R_NAME varchar(50),R_COMMENT varchar(50));
insert into test_shard (id,R_bit,R_NAME,R_COMMENT) values (1,b'0001', 'a','test001'),(2,b'0010', 'a string','test002'),(3,b'0011', '1','test001'),(4,b'1010', '1','test001');

• configs：

schema.xml

<schema name="mytest" sqlMaxLimit="100" dataNode="dn5">
           <table name="test_shard" dataNode="dn1,dn2,dn3,dn4" rule="hash-four"/>
</schema>

rule.xml

tableRule name="hash-four">
        <rule>
            <columns>id</columns>
            <algorithm>four-long</algorithm>
        </rule>
    </tableRule>
<function name="four-long" class="Hash">
		<property name="partitionCount">4</property>
		<property name="partitionLength">1</property>
	</function>

server.xml

• steps：
  step1. Run the following python script

import MySQLdb
conn=MySQLdb.connect('10.186.65.63','test','test','mytest',8066,autocommit=True)
cur=conn.cursor()
def my_insert():
    for i in range(0,100):
        cur.execute("select * from test_shard where HEX(R_bit) not like (select '%A%') escape (select '%')")
        rs = cur.fetchone()
my_insert()

• expect result：
  1. execute successed
• real result：
  1. The python script will hang or give an error:2013, 'Lost connection to MySQL server during query'
• supplements：
  1.dble log：
  关键log.txt

/label ~BUG

[yanhuqing666]

fixed in c2b0c0a

[FlyingMao]

verified version: 5.6.29-dble-9.9.9.9-c60b90b31aad56503ff71ae8ffd8e6e271a207f1-20190103085956