Proxy database not switching - spring

Question

Spring framework 4.1.4
Spring batch 3.0.2
Tomcat 7
Morning,
I have successfully used a configuration based on Marten Deinum's Post
to dynamically connect (or create and connect) to dbs only known at run time.
The problem I am having is the process now intermittently fails to switch between dbs. The first always works but putting in logging code shows the first properly being created and then the second or third not firing dataSource == null section in the MdyDataSourceFactory - it appears if the process thinks it is the same db and so doesn't change but at some point it triggers and connects to a subsequent db!
Running a simple JUnit test switching between dbs works fine (code correctly fires and dbs switch and select statement returns different id results as expected).
It is being called within a Batch Job step tasklet. The process grabs a count of resultSets (summary table) and connects to the db. For each resultSet it calls the db registry and if exists - returns existing or creates a new one and returns.
My dynamic db xml is:
<bean id="mdyDSRegistry" class="com.k12knowledge.db.MdyDataSourceFactory" />
<bean id="mdyDSTargetSource" class="com.k12knowledge.db.ContextSwappableMdyTargetSource">
<constructor-arg type="java.lang.Class">
<value>javax.sql.DataSource</value>
</constructor-arg>
<property name="targetRegistry" ref="mdyDSRegistry"></property>
</bean>
<bean id="proxyMdyDataSource" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="proxyInterfaces">
<list>
<value>javax.sql.DataSource</value>
</list>
</property>
<property name="targetSource">
<ref bean="mdyDSTargetSource" />
</property>
</bean>
The MdyDataSourceFactory is:
public class MdyDataSourceFactory implements TargetRegistry {
private ConcurrentMap<String, DataSource> map = new ConcurrentHashMap<String, DataSource>();
#Override
public DataSource getTarget(String context) {
IClientDs client = MdyContextHolder.getClientDs();
Assert.notNull(client, "Client was not set.");
String key = client.getUrl();
DataSource dataSource = map.get(key);
if (dataSource == null) {
System.out.println("dataSource == null - creating new");
dataSource = getDataSource(client);
dataSource = map.putIfAbsent(key, dataSource);
if (dataSource == null) {
// put success
dataSource = map.get(key);
}
}
System.out.println("client key: " + key);
return dataSource;
}
private DataSource getDataSource(IClientDs client) {
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName(client.getDriver());
dataSource.setUrl(client.getUrl());
dataSource.setUsername(client.getUsername());
dataSource.setPassword(client.getPassword());
dataSource.setValidationQuery("/* ping */");
dataSource.setMaxActive(10);
dataSource.setMaxIdle(5);
dataSource.setTestOnBorrow(true);
dataSource.setTestWhileIdle(true);
dataSource.setRemoveAbandoned(true);
dataSource.setRemoveAbandonedTimeout(20);
dataSource.setTimeBetweenEvictionRunsMillis(34000);
dataSource.setMinEvictableIdleTimeMillis(55000);
try {
System.out.println("dataSource " + client.getUrl() + " closed ? " + dataSource.getConnection().isClosed());
} catch (SQLException e) {
e.printStackTrace();
}
return dataSource;
}
}
At one point I thought there was an issue with the key I used (some databases are only different in name by 1 letter). I then tried adding an UUID to the front of the key to see if that was the issue - no change.
Really puzzled as to why it is not working... Any pointers greatly appreciated.
Thank you for looking.
ContextHolder
public abstract class ContextHolder {
private static final ThreadLocal<IClientDs> holder = new ThreadLocal<IClientDs>();
public static void setClientDs(IClientDs context) {
LoggerFactory.getLogger(ContextHolder.class).debug("context set '{}'", context);
holder.set(context);
}
public static IClientDs getClientDs() {
return (IClientDs) holder.get();
}
}