C3P0 Managed connection pool could not acquire a resource from its primary or factory resource

Question

I am using Postgresql as my underlying Database and and letting Spring managed my DataSource/Connection pool. The configuration I have is this

<bean id="clientDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass" value="org.postgresql.Driver"/>
        <property name="jdbcUrl" value="jdbc:postgresql://localhost:5432/genesis_cms"/>
        <property name="user" value="user"/>
        <property name="password" value="password"/>
    </bean>


    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="clientDataSource"/>
        <property name="packagesToScan"  value = "org.myproject.package.commons.model.*"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.dialect">${hibernate.sql.dialect}</prop>
                <prop key="hibernate.connection.pool_size">${hibernate.connection.pool_size}</prop>
                <prop key="hibernate.format_sql">true</prop>
                <prop key="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</prop>
                <prop key="hibernate.connection.driver_class">org.postgresql.Driver</prop>
                <prop key="show_sql">true</prop>
                <prop key="hibernate.c3p0.min_size">5</prop>
                <prop key="hibernate.c3p0.max_size">15</prop>
                <prop key="hibernate.c3p0.timeout">300</prop>
                <prop key="hibernate.c3p0.max_statements">50</prop>
                <prop key="hibernate.c3p0.idle_test_period">3000</prop>

SCHEMA org.myproj.hibernate.SchemaResolver org.myproj.hibernate.MultitenantConnectionProvider

          </props>
        </property>
    </bean>

    <bean id = "transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

However, whenever I am booting up my application this log message appears.

 Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@88f0b8ea [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@ce8fda44 [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> false, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge0yw969iurgbvtwis0|6ee5f485, idleConnectionTestPeriod -> 3000, initialPoolSize -> 5, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 300, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 50, maxStatementsPerConnection -> 0, minPoolSize -> 5, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@ce2ef138 [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge0yw969iurgbvtwis0|ccd341d, jdbcUrl -> null, properties -> {} ], preferredTestQuery -> null, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge0yw969iurgbvtwis0|53eba4b8, numHelperThreads -> 3 ]

I believe I have configured my settings correctly, Any idea how to debug this or solve this?

The Exception I am getting.

com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
    at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1418)
    at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:606)
    at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:526)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:755)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:682)
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140)
    at org.hibernate.c3p0.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:89)
    at com.brightworks.genesis.client.config.hibernate.MultitenantConnectionProvider.getAnyConnection(MultitenantConnectionProvider.java:49)
    at com.brightworks.genesis.client.config.hibernate.MultitenantConnectionProvider.getConnection(MultitenantConnectionProvider.java:55)
    at org.hibernate.internal.AbstractSessionImpl$ContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:423)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:228)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:171)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:63)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:162)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:186)
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:160)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1884)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1861)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1838)
    at org.hibernate.loader.Loader.doQuery(Loader.java:909)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:354)
    at org.hibernate.loader.Loader.doList(Loader.java:2553)
    at org.hibernate.loader.Loader.doList(Loader.java:2539)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2369)
    at org.hibernate.loader.Loader.list(Loader.java:2364)
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:496)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:387)
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:231)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1264)
    at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103)
    at org.hibernate.jpa.internal.QueryImpl.list(QueryImpl.java:573)
    at org.hibernate.jpa.internal.QueryImpl.getSingleResult(QueryImpl.java:495)
    at org.hibernate.jpa.criteria.compile.CriteriaQueryTypeQueryAdapter.getSingleResult(CriteriaQueryTypeQueryAdapter.java:71)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$DeferredQueryInvocationHandler.invoke(SharedEntityManagerCreator.java:360)
    at com.sun.proxy.$Proxy52.getSingleResult(Unknown Source)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$SingleEntityExecution.doExecute(JpaQueryExecution.java:197)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:74)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:97)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:88)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:421)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:381)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$DefaultMethodInvokingMethodInterceptor.invoke(RepositoryFactorySupport.java:512)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:266)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodIntercceptor.invoke(CrudMethodMetadataPostProcessor.java:111)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
    at com.sun.proxy.$Proxy41.findByUsername(Unknown Source)
    at org.brightworks.genesis.commons.service.account.impl.AccountServiceImpl.findByUsername(AccountServiceImpl.java:25)
    at com.brightworks.genesis.client.webapp.controller.ProductController.addProductForm(ProductController.java:34)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:769)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1667)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:144)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
    at com.googlecode.webutilities.filters.CompressionFilter.doFilter(CompressionFilter.java:131)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:583)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1125)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1059)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:215)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:110)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
    at org.eclipse.jetty.server.Server.handle(Server.java:497)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:248)
    at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:540)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:610)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:539)

And this one

- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
java.lang.NullPointerException
        at org.postgresql.Driver.parseURL(Driver.java:591)
        at org.postgresql.Driver.acceptsURL(Driver.java:429)
        at java.sql.DriverManager.getDriver(DriverManager.java:299)
        at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:240)
        at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:131)
        at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:156)
        at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:145)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:200)
        at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1086)
        at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1073)
        at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:44)
        at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1810)
        at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:648)

And here's my MultiTenantIdentifier

public class MultitenantConnectionProvider implements MultiTenantConnectionProvider, ServiceRegistryAwareService {

    private static final long serialVersionUID = 4368575201221677384L;

    private C3P0ConnectionProvider connectionProvider = null;

    @Override
    public boolean supportsAggressiveRelease() {
        return false;
    }

    @Override
    public void injectServices(ServiceRegistryImplementor serviceRegistry) {
        Map lSettings = serviceRegistry.getService(ConfigurationService.class).getSettings();

        connectionProvider = new C3P0ConnectionProvider();
        connectionProvider.injectServices(serviceRegistry);
        connectionProvider.configure(lSettings);

    }

    @Override
    public boolean isUnwrappableAs(Class clazz) {
        return false;
    }

    @Override
    public <T> T unwrap(Class<T> clazz) {
        return null;
    }

    @Override
    public Connection getAnyConnection() throws SQLException {
        final Connection connection = connectionProvider.getConnection();
        return connection;
    }

    @Override
    public Connection getConnection(String tenantIdentifier) throws SQLException {
        final Connection connection = getAnyConnection();
        try {
            connection.createStatement().execute("SET SCHEMA '" + tenantIdentifier + "'");
        }
        catch (SQLException e) {
            throw new HibernateException("Could not alter JDBC connection to specified schema [" + tenantIdentifier + "]", e);
        }
        return connection;
    }

    @Override
    public void releaseAnyConnection(Connection connection) throws SQLException {
        try {
            connection.createStatement().execute("SET SCHEMA 'public'");
        }
        catch (SQLException e) {
            throw new HibernateException("Could not alter JDBC connection to specified schema [public]", e);
        }
        connectionProvider.closeConnection(connection);
    }

    @Override
    public void releaseConnection(String tenantIdentifier, Connection connection) throws SQLException {
        releaseAnyConnection(connection);
    }
}

and My Schema Resolver

public class SchemaResolver implements CurrentTenantIdentifierResolver {

    @Override
    public String resolveCurrentTenantIdentifier() {

        return "tenant1"; //TODO: Implement service to identify tenant like: userService.getCurrentlyAuthUser().getTenantId();
    }

    @Override
    public boolean validateExistingCurrentSessions() {
        return false;
    }
}

EDIT:

ADDTIONAL INFO:

The configurations I've set to the xml I pasted is not being reflected upon runtime. inside the client data source, I've specified the jdbc url, however when checking the logs at run time, it wasn't being reflected hence the 'jdbc -> null'

I pasted the wrong configuration, it turns out that I have configured hibernate as Mutlti-tenancy with SchemaResolver and MultiTenantConnection Provider

Answer 1

To those of you who were having the same problem as I did. Here's the findings and the solution I have.

1.) Based on my XML configuration, I have already configured the DataSource(In this case, The C3P0ComboPooledDataSource).

2.) On my MultiTenantIdentifier, I was again, configuring I have hard a coded Dependency, The C3P0ConnectionProvider. The configurations overrides the one I've specified on my clientDataSource bean. The configuration of the C3P0ConnectionProvider at is configured at this line.

<property name="jpaProperties">
            <props>
.....</props>
</property>

Which in this case, does not have jdbcUrl,Driver, and etc.

Conclusion, My bean configuration at clientDataSource is being overriden by the hard coded dependency.

Solution.

Instead of creating a new DataSource in my MultitenantConnectionProvider. Just use the only that exists/being created by my bean. like this

public class MultitenantConnectionProvider implements MultiTenantConnectionProvider, ServiceRegistryAwareService {

    private static final long serialVersionUID = 4368575201221677384L;

    private org.slf4j.Logger logger = LoggerFactory.getLogger(MultitenantConnectionProvider.class);

    private DataSource lazyDatasource = null;

    @Override
    public boolean supportsAggressiveRelease() {
        return false;
    }

    /**
     * The DataSource/ConnectionPool we are using is the one configured by the environment
     * Which by default, in our case, is configured at client-persistence-cfg.xml
     * (named Client Data Source)
     */
    @Override
    public void injectServices(ServiceRegistryImplementor serviceRegistry) {
        Map lSettings = serviceRegistry.getService(ConfigurationService.class).getSettings();
        lazyDatasource = (DataSource) lSettings.get(Environment.DATASOURCE);
    }

    @Override
    public boolean isUnwrappableAs(Class clazz) {
        return false;
    }

    @Override
    public <T> T unwrap(Class<T> clazz) {
        return null;
    }

    /**
     * Retrieve any connection from the Connection Pool
     */
    @Override
    public Connection getAnyConnection() throws SQLException {
        return lazyDatasource.getConnection();
    }

    @Override
    public Connection getConnection(String tenantIdentifier) throws SQLException {
        final Connection connection = getAnyConnection();
        try {
            connection.createStatement().execute("SET SCHEMA '" + tenantIdentifier + "'");
        }
        catch (SQLException e) {
            throw new HibernateException("Could not alter JDBC connection to specified schema [" + tenantIdentifier + "]", e);
        }
        return connection;
    }

    @Override
    public void releaseAnyConnection(Connection connection) throws SQLException {
        try {
            connection.createStatement().execute("SET SCHEMA 'public'");
        }
        catch (SQLException e) {
            throw new HibernateException("Could not alter JDBC connection to specified schema [public]", e);
        }
        connection.close();
    }

    @Override
    public void releaseConnection(String tenantIdentifier, Connection connection) throws SQLException {
        releaseAnyConnection(connection);
    }
}

Next, configuration files.

<bean id="clientDataSource" class="com.zaxxer.hikari.HikariDataSource" destroy-method="close">
    <property name="driverClassName" value="${driver.className}"/>
    <property name="jdbcUrl" value="${db.url}"/>
    <property name="username" value="${db.username}"/>
    <property name="password" value="${db.password}"/>
    <property name="maximumPoolSize" value="30" />
    <property name="connectionTestQuery" value="SELECT 1" />
</bean>

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="clientDataSource"/>
    <property name="packagesToScan"  value = "org.brightworks.genesis.commons.model"/>
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="databasePlatform" value="${hibernate.sql.dialect}" />
            <property name="showSql" value="true" />
        </bean>
    </property>
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.format_sql">true</prop>
            <prop key="hibernate.multiTenancy">SCHEMA</prop>
            <prop key="hibernate.tenant_identifier_resolver">com.myprojec.SchemaResolver</prop>
            <prop key="hibernate.multi_tenant_connection_provider">com.myproj.hibernate.MultitenantConnectionProvider</prop>
        </props>
    </property>
</bean>

Conclusion: Just retrieve the current/available DataSource that's configured by Spring.