Mybatis insert freezes when done in a task - spring

Question

I have an sql session thus defined:
<tx:annotation-driven transaction-manager="transactionManager" />
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource" />
</bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
</bean>
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
<constructor-arg index="0" ref="sqlSessionFactory" />
<constructor-arg index="1" value="BATCH" />
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="..." />
</bean>
<bean id="taskExecutor"
class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
<property name="corePoolSize" value="5" />
<property name="maxPoolSize" value="10" />
<property name="queueCapacity" value="25" />
</bean>
Now, in my service, I have to make some select on a table and some inserts in a different table.
#Transactional
public class MyWebService{
#Autowired
private TaskExecutor executor;
#Autowired
private SelectTableMapper sm;
#Autowired
private InsertTableMapper it;
public void service(){
int rowCount = ...//getting row count
int batch = rowCount/numThreads;
//computing an interval for each thread with non overlapping rows
for(int i=0;i<numThread;i++)
executor.execute(new MyTask(//interval//));
..waiting for all tasks and finally returning
}
private class MyTask implements Runnable{
public void run(){
List<Row> rows = sm.select(//interval//);
for(Row row : rows){
if(//some condition//)
it.insert(row); //if I comment here it successfully completes
}
}
}
}
Problem is that program just freezes! And I am sure it is not my logic's fault because program successfully ends by commenting the insertion line.
So I guess it is a concurrency problem on the second table, the one I am inserting data in.