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ConcurrentModificationException when Hibernate Upgrade from 4.x to 5.x and Spring 4.x for Multi-Threaded

I am having an issue when we migrated from Hibernate 4 to 5.
I have been struggling from a week and read numerous blogs and pages, but could not resolve.
Following are more information on the issue:-
1) Hibernate Version :
From: 4.3.11.Final
To : 5.4.28.Final
2) Spring ORM version : 4.3.29.RELEASE
3) Spring Batch Infrastructre/Core: 3.0.10.Release
4) Hibernate XML Configuration :
<?xml version="1.0" encoding="UTF-8"?>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
<property name="dataSource">
<ref bean="dataSource"/> <!-- set in another xml using org.apache.commons.dbcp.BasicDataSource -->
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.id.new_generator_mappings">true</prop>
<!-- -->
<prop key="hibernate.jdbc.batch_size">1000</prop>
<prop key="hibernate.jdbc.fetch_size">1000</prop>
<prop key="hibernate.order_inserts">true</prop>
<prop key="hibernate.order_updates">true</prop>
</props>
</property>
<property name="annotatedClasses">
<list>
<value>com.company.ParentTable</value>
<value>com.company.ChildTable</value>
</list>
</property>
</bean>
<bean id="transactionTemplate"
class="org.springframework.transaction.support.TransactionTemplate"
p:isolationLevelName="ISOLATION_READ_COMMITTED"
p:propagationBehaviorName="PROPAGATION_REQUIRES_NEW"
p:transactionManager-ref="transactionManager"
/>
<tx:annotation-driven transaction-manager="transactionManager"/>
<!-- Spring transaction management -->
<bean id="transactionManager"
class="org.springframework.orm.hibernate5.HibernateTransactionManager"
p:sessionFactory-ref="sessionFactory"
/>
5) Spring Batch Configuration
<?xml version="1.0" encoding="UTF-8"?>
<batch:job id="loaderJob" job-repository="jobRepository">
<batch:step id="initLoader" next="pipeline">
<batch:tasklet transaction-manager="transactionManager">
<bean class="com.company.InitialLoaderTask" scope="step">
<constructor-arg name="dao" ref="dao"/>
<constructor-arg name="filter" value="#{jobParameters['filter']}"/>
</bean>
</batch:tasklet>
</batch:step>
<batch:step id="pipeline">
<batch:tasklet transaction-manager="transactionManager" task-executor="loader_multi_thread_taskExecutor" throttle-limit="50">
<batch:chunk
reader="reader"
writer="processorAndWriter"
commit-interval="1000">
</batch:tasklet>
</batch:step>
</batch:job>
<bean id="reader" class="com.company.SynchronizedItemStreamReader" scope="step" > <!-- Custom Synchrnized Item Reader -->
<constructor-arg name="delegate" ref="#{ jobExecutionContext['region'] ? 'hibernateReader':'hibernateReader2' }"/> <!-- hibernateReader2 is same as hibernateReader but with more params -->
</bean>
<bean id="hibernateReader"
class="org.springframework.batch.item.database.HibernateCursorItemReader"
scope="step" >
<property name="sessionFactory" ref="sessionFactory"/>
<property name="queryName" value="ParentTable.query1"/>
<property name="useStatelessSession" value="false"/>
<property name="saveState" value="false"/>
<property name="fetchSize" value="10000"/>
<property name="parameterValues">
<map>
<entry key="param1" value="#{jobExecutionContext['param1']}"/>
<entry key="param2" value="#{jobExecutionContext['param2']}"/>
</map>
</property>
</bean>
<bean id="processorAndWriter"
class="com.company.LoaderAndWriter"
>
<constructor-arg name="generator" ref="processor"/>
<constructor-arg name="writer" ref="hibernateWriter"/>
</bean>
<bean id="processor" class="org.springframework.batch.item.support.CompositeItemProcessor" >
<property name="delegates">
<list>
<bean class="com.company.Generator" scope="step">
<constructor-arg name="param1" value="#{jobExecutionContext['param1']}"/>
</bean>
<bean class="com.company.Processor" scope="step">
<constructor-arg name="param3" value="#{jobExecutionContext['param3']}"/>
</bean>
</list>
</property>
</bean>
<bean id="hibernateWriter" class="org.springframework.batch.item.database.HibernateItemWriter">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
<bean id="loader_multi_thread_taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
<property name="corePoolSize" value="25"/>
<property name="maxPoolSize" value="50"/>
</bean>
6) Entity Objects
#Entity
#Table(name = "PARENT_TABLE")
#NamedNativeQueries({
#NamedNativeQuery(
name = "ParentTable.query1",
query = "SELECT * FROM PARENT_TABLE where param = :param1",
resultClass = ParentTable.class
)
})
#BatchSize(size = 1000)
public class ParentTable extends PersistentEntity<Long> {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "PARENT_TABLE_SEQ")
#SequenceGenerator(name = "PARENT_TABLE_SEQ", sequenceName = "PARENT_TABLE_SEQ", allocationSize=5)
private Long id;
#Column
private Long field1;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "fieldId", fetch = FetchType.EAGER)
#BatchSize(size = 1000)
private List<ChildTable> childTable;
}
#Entity
#Table(name = "CHILD_TABLE")
#BatchSize(size = 1000)
public class ChildTable extends PersistentEntity<Long> {
private static final long serialVersionUID = 1L;
#Id
private Long id;
#ManyToOne
#JoinColumn(name = "field1")
private ParentTable parentData;
#Column
private String field2;
}
7) Generator Class where error is thrown when access Childtable data from ParentData List
public class Generator implements ItemProcessor<List<? extends ParentTable>, RequestPojoBean> {
private final int param1;
public Generator(int param1) {
this.param1 = param1;
}
#Override
public RequestPojoBean process(List<? extends ParentTable> parentDataList) throws Exception {
RequestPojoBean result = new RequestPojoBean();
result.setParentDataList(convertToRequestList(parentDataList));
result.setparam1(param1);
return result;
}
private List<ParentRequestPojoBean> convertToRequestList(List<? extends ParentTable> parentDataList) {
List<ParentRequestPojoBean> parentRequestBean = new ArrayList<>();
for (ParentTable parentData : parentDataList) {
LOGGER.info("Parent detail " + parentData.getField1());
ParentRequestPojoBean bean1 = new ParentRequestPojoBean();
bean1.setSomeData(callToSomeServiceViaHibernate(parentData.somedata, param1));
// attach References if any
List<RequestPojoBeanChildData> childList = new ArrayList<>();
for (ChildTable child : parentData.getChildTable()) { *****<--- Exception is thrown at this line*****
RequestPojoBeanChildData childPojoData = new RequestPojoBeanChildData();
childPojoData.setField2(child.getField2());
childList.add(childPojoData);
}
bean1.setChildData(childList);
parentRequestBean.add(bean1);
}
return parentRequestBean;
}
}
8) Exception Stack Trace :
2021-04-12 13:33:42,548 ERROR [main] [org.springframework.batch.core.step.AbstractStep] - <Encountered an error executing step pipeline in job loaderJob>
java.util.ConcurrentModificationException
at java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:719)
at java.util.LinkedHashMap$LinkedEntryIterator.next(LinkedHashMap.java:752)
at java.util.LinkedHashMap$LinkedEntryIterator.next(LinkedHashMap.java:750)
at org.hibernate.engine.spi.BatchFetchQueue.getCollectionBatch(BatchFetchQueue.java:311)
at org.hibernate.loader.collection.plan.LegacyBatchingCollectionInitializerBuilder$LegacyBatchingCollectionInitializer.initialize(LegacyBatchingCollectionInitializerBuilder.java:79)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710)
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:93)
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2163)
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589)
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264)
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585)
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149)
at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:387)
As part of migration, I have updated
Hibernate version
Hibernate5.LocalSessionFactoryBean
Hibernate5.HibernateTransactionManager
If I revert back above mentioned changes for Hibernate4, the code works fine in Multi-Threaded Pool, but throws ConcurrentModificationException with above updates.
I am sure I must be missing something very silly OR some setting which needs to be added as part of Hibernate 5 migration.
Any suggestion is greatly appreciated.
Thanks in advance.

An Hibernate Session and the objects loaded from that session, altogether, are not thread safe. So you cannot load objects from a session and then use these objects in different threads.
Among other problems these objects might trigger the initialization of lazy collection/proxies, which ultimately falls on the underlying JDBC connection and that connection is not thread safe either.
You need to give each thread it's own session and you must not share objects loaded from sessions between threads

How to get the value from a #JoinColumn using Spring batch and Hibernate

Introduction
In order to extract some data from a database, I am trying to setup a basic hibernate and spring batch project. The goal is to provide one query (HQL) and based on this query the spring batch application extracts all the data to a flat file.
One of the requirements of the application is that the user should not have to configure the mappings of the columns. As such I am trying to create a DynamicRecordProcessor that evaluates the input and passes the input (a table for example Address) to the writer in such a way that the flat file item writer can use a PassThroughFieldExtractor.
Below the reader-processor-writer xml configuration:
<!-- Standard Spring Hibernate Reader -->
<bean id="hibernateItemReader" class="org.springframework.batch.item.database.HibernateCursorItemReader">
<property name="sessionFactory" ref="sessionFactory" />
<property name="queryString" value="from Address" />
</bean>
<!-- Custom Processor -->
<bean id="dynamicRecordProcessor" class="nl.sander.mieras.processor.DynamicRecordProcessor"/>
<!-- Standard Spring Writer -->
<bean id="itemWriter" class="org.springframework.batch.item.file.FlatFileItemWriter">
<property name="resource" value="file:target/extract/output.txt" />
<property name="lineAggregator">
<bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
<property name="delimiter" value="|"/>
<property name="fieldExtractor">
<bean class="org.springframework.batch.item.file.transform.PassThroughFieldExtractor"/>
</property>
</bean>
</property>
</bean>
EDIT:
And the job configuration:
<bean id="jobLauncher" class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
<property name="jobRepository" ref="jobRepository" />
</bean>
<bean id="jobRepository" class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean">
<property name="transactionManager" ref="transactionManager"/>
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
<property name="configLocation" value="classpath:hibernate.cfg.xml"/>
<property name="cacheableMappingLocations" value="classpath*:META-INF/mappings/*.hbm.xml"/>
</bean>
<bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager" lazy-init="true">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
Problem
My processor looks as following:
public class DynamicRecordProcessor<Input,Output> implements ItemProcessor<Input,Output> {
private static final String DELIMITER = "|";
private boolean areNamesSetup = false;
private List<String> names = new ArrayList<String>();
private Input item;
#SuppressWarnings("unchecked")
#Override
public Output process(Input item) throws Exception {
this.item = item;
initMapping();
return (Output) extract();
}
private void initMapping() {
if (!areNamesSetup) {
mapColumns();
}
areNamesSetup = true;
}
private void mapColumns() {
Field[] allFields = item.getClass().getDeclaredFields();
for (Field field : allFields) {
if (!field.getType().equals(Set.class) && Modifier.isPrivate(field.getModifiers())) {
names.add(field.getName());
}
}
}
private Object extract() {
List<Object> values = new ArrayList<Object>();
BeanWrapper bw = new BeanWrapperImpl(item);
for (String propertyName : this.names) {
values.add(bw.getPropertyValue(propertyName));
}
return StringUtils.collectionToDelimitedString(values, DELIMITER);
}
}
The table Address has the following field:
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name="city_id", nullable=false)
public City getCity() {
return this.city;
}
And the corresponding column in city:
#Column(name="city_id", unique=true, nullable=false)
public Short getCityId() {
return this.cityId;
}
When using values.add(bw.getPropertyValue(propertyName)); with propertyName being "city" the following exception occurs:
org.hibernate.SessionException: proxies cannot be fetched by a stateless session
at org.hibernate.internal.StatelessSessionImpl.immediateLoad(StatelessSessionImpl.java:292)
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:156)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:260)
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:68)
at nl.sander.mieras.localhost.sakila.City_$$_jvstc2c_d.toString(City_$$_jvstc2c_d.java)
at java.lang.String.valueOf(String.java:2982)
at java.lang.StringBuilder.append(StringBuilder.java:131)
at org.springframework.util.StringUtils.collectionToDelimitedString(StringUtils.java:1132)
at org.springframework.util.StringUtils.collectionToDelimitedString(StringUtils.java:1148)
at nl.sander.mieras.processor.DynamicRecordProcessor.extract(DynamicRecordProcessor.java:52)
at nl.sander.mieras.processor.DynamicRecordProcessor.process(DynamicRecordProcessor.java:27)
The value, however, is availabe as shown in the screenshot below.
Concrete question: How can I get the value 300?
I have tried getting the value using reflection API, but I couldn't reach the actual value I want to get...
Reproduce
I have setup a public repo. However, you still need a local database to be able to reproduce exactly the issue. https://github.com/Weirdfishees/hibernate-batch-example. Any suggestions how isolate this issue further are more then welcome.

Just flip your reader to be state-full instead of stateless with the useStatelessSession property:
<!-- Standard Spring Hibernate Reader -->
<bean id="hibernateItemReader" class="org.springframework.batch.item.database.HibernateCursorItemReader">
<property name="sessionFactory" ref="sessionFactory" />
<property name="queryString" value="from Address" />
<property name="useStatelessSession" value="false" />
</bean>

JdbcTemplate not work when use #Transactional annotation

When use spring data and jdbctemplate in same function
spring data work fine but jdbc update not work .
this is service class.
jdbc update then not error occurred but database not updated
#Service
public class SampleService {
private static final Logger logger = LoggerFactory.getLogger(SampleService.class);
#Inject
private SampleRepository sampleRepository;
#Inject
private JpaTransactionManager transactionManager;
private JdbcTemplate jdbcTemplate() {
return new JdbcTemplate(transactionManager.getDataSource());
}
#Transactional(propagation=Propagation.REQUIRED)
public void execute(){
sampleRepository.deleteAll();
sampleRepository.save(new Sample("sample"));
logger.info("data count (after jpa insert) : {}", sampleRepository.count());//1
int count = jdbcTemplate().update("insert into Sample (sample) values ( ? )", "sample");
logger.info("jdbc insert count: {}", count);//1
logger.info("data count (after jdbc insert) : {}", sampleRepository.count());//expected: 2 , actual:1
count = jdbcTemplate().queryForObject("select count(id) from Sample", Integer.class);
logger.info("data count (after jdbc insert) : {}", count); //jdbc count query result also return 1
}
when not use #Transactional annotation then work fine.
public void execute2(){
DefaultTransactionDefinition def = new DefaultTransactionDefinition();
def.setName("testTx");
def.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
TransactionStatus status = transactionManager.getTransaction(def);
... this method work fine ...
transactionManager.commit(status);
}
}
and this is data access configuration.
<context:annotation-config />
<tx:jta-transaction-manager />
<tx:annotation-driven transaction-manager="transactionManager" />
<jpa:repositories base-package="example" />
<context:property-placeholder location="classpath:config.properties" />
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="persistenceUnitName" value="DefaultUnit" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="showSql" value="${db.showsql}" />
<property name="generateDdl" value="${db.generateDDL}" />
<property name="database" value="${db.database}" /><!-- H2 -->
</bean>
</property>
</bean>
<bean id="dataSource" class="org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy">
<constructor-arg ref="basicDataSource" />
</bean>
<bean id="basicDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${db.driver}" />
<property name="url" value="${db.url}" />
<property name="username" value="${db.user}" />
<property name="password" value="${db.pass}" />
<property name="defaultAutoCommit" value="false" />
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

Tansactional context of Spring and Spring-data-jpa

I'm working on a import module, where I'm reading from an excel file, fill the entities and save them.
Now my trouble is that I'm working with many entities and then i split the save on DB in three distinct methods.
This is my import method:
#Transactional(propagation = Propagation.REQUIRES_NEW)
private void readRowFromExcel(Row row){
for(Row row : sheet){
Customer customer = readCustomerFromExcel(row)
CustomerDeatails customerDetails = readCustomerDetailsFromExcel(row)
customerService.save(customer,customerDetails);
MyEntity myEntity = readMyEntityFromExcel(row);
myEntityService.save(myEntity)
}
}
This is the save method in the customer service
#Transactional(propagation = Propagation.REQUIRED)
public void save(Customer customer, CustomerDetails customerDetails){
customerRepository.save(customer);
customerDatailsRepository.save(customer);
}
This is the save method in the myEntity service:
#Transactional(propagation = Propagation.REQUIRED)
public void save(MyEntity myEntity){
myEntityRepository.save(myEntity)
}
Now my trouble is that if i get an exception on the following code line
MyEntity myEntity = readMyEntityFromExcel(row);
the entities customer and customerDetails are already persistent, while i should save only if everything works
My spring-context.xml
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="${db.driverClass}" />
<property name="url" value="${db.connectionURL}" />
<property name="username" value="${db.username}" />
<property name="password" value="${db.password}" />
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"
p:entityManagerFactory-ref="entityManagerFactory">
<property name="persistenceUnitName" value="myUnit" />
</bean>
<!--
<bean id="hibernateJpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<description>Allow spring to configure hibernate specific settings</description>
</bean>
-->
<bean id="eclipseLinkJpaVendorAdapter" class="org.springframework.orm.jpa.vendor.EclipseLinkJpaVendorAdapter">
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
p:dataSource-ref="dataSource"
p:persistenceUnitName="myUnit"
p:jpaVendorAdapter-ref="eclipseLinkJpaVendorAdapter">
<property name="jpaPropertyMap">
<map>
<entry key="eclipselink.cache.shared.default" value="false" />
<entry key="eclipselink.weaving" value="false" />
</map>
</property>
<property name="loadTimeWeaver">
<bean
class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" />
</property>
</bean>
<tx:annotation-driven transaction-manager="transactionManager" />
How can i do to solve it?

The solution is simple: you move the lines that read from excel before any DB persisting is made:
#Transactional(propagation = Propagation.REQUIRES_NEW)
private void readRowFromExcel(Row row){
for(Row row : sheet){
//Reading from Excel
Customer customer = readCustomerFromExcel(row)
CustomerDeatails customerDetails = readCustomerDetailsFromExcel(row);
MyEntity myEntity = readMyEntityFromExcel(row);
//DB persisting
customerService.save(customer,customerDetails);
myEntityService.save(myEntity)
}
}

Not routing DataSource with Spring 3 and MyBatis

I have a default database and sometimes I have to make a select in another database.
I've searched many blogs and questions here about this, but couldn't make it work.
Tried the http://blog.springsource.org/2007/01/23/dynamic-datasource-routing/ way. Nothing.
Code for RouterDataSource class:
public class RouterDataSource extends AbstractRoutingDataSource {
#Override
protected DataSourceEnum determineCurrentLookupKey() {
return DataSourceContextHolder.getTargetDataSource();
}
}
Code for DataSourceContextHolder class:
public class DataSourceContextHolder {
private static final ThreadLocal<DataSourceEnum> contextHolder = new ThreadLocal<DataSourceEnum>();
public static void setTargetDataSource(DataSourceEnum targetDataSource) {
Assert.notNull(targetDataSource, "Target data source cannot be null");
contextHolder.set(targetDataSource);
}
public static DataSourceEnum getTargetDataSource() {
if (contextHolder.get() != null)
return (DataSourceEnum) contextHolder.get();
else
return DataSourceEnum.DB1;
}
public static void resetDefaultDataSource() {
contextHolder.remove();
}
}
Code for the method calling to change the database:
#Override
public CodeHD getCategoryByCode(String code) throws BusinessException {
DataSourceContextHolder.setTargetDataSource(DataSourceEnum.DATABASE2);
return (CodeHD) persistency.getObject(GETOBJECT_BY_CODE, code);
}
Code for DatasourceEnum class:
public enum DataSourceEnum {
DB1,
DB2;
}
And finally the configuration on my applicationContext.xml:
<bean id="parentDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" abstract="true">
<property name="driverClass" value="oracle.jdbc.pool.OracleDataSource" />
<property name="acquireIncrement" value="10" />
<property name="idleConnectionTestPeriod" value="60" />
<property name="maxStatements" value="50" />
<property name="minPoolSize" value="5" />
<property name="maxPoolSize" value="15" />
</bean>
<bean id="database1DS" parent="parentDataSource">
<property name="jdbcUrl" value="jdbc:oracle:thin:#database1:1521:xe" />
<property name="user" value="user" />
<property name="password" value="password" />
</bean>
<bean id="database2DS" parent="parentDataSource">
<property name="jdbcUrl" value="jdbc:oracle:thin:#database2:1521:xe" />
<property name="user" value="user" />
<property name="password" value="password" />
</bean>
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<bean id="dataSource" class="package.RouterDataSource">
<property name="defaultTargetDataSource" ref="database1DS"/>
<property name="targetDataSources">
<map key-type="package.DataSourceEnum">
<entry key="DB1" value-ref="database1DS"/>
<entry key="DB2" value-ref="database2DS"/>
</map>
</property>
</bean>
The problem is that when I set it to DB2 it won't change.
Can anyone help me?

Try to make both static method as non static and pass R reference if the context holder.

First make sure that database2DS is working correctly. Make the defaultTargetDatasource database2DS and verify that it is not using DB1 still and there are no other errors using database2DS as the default. If the AbstractRoutingDataSource fails to resolve a DataSource in the targetDataSources you cannot switch to it.
AbstractRoutingDataSource will only change the DataSource when getConnection is called. Whatever persistence framework you're using is probably caching the Connection and not calling getConnection in between persistency.getObject(). However you are getting your persistency object, try getting a new persistency object after you change the datasource in DataSourceContextHolder. If this solves your problem, try creating a class that maintains your persistency object and handles changing the datasource. That way when you change the datasource you can modify your persistency manager object in one spot.