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First connection org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection

I'm having problems with a server in Spring 4 and Mysql with Hibernate, Every first connection it is answering me org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
My properties.xml is:
<persistence-unit name="defaultPersistenceUnit"
transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
<property name="hibernate.connection.url"
value="jdbc:mysql://mysql.******?reconnect=true" />
<property name="hibernate.connection.username" value="root" />
<property name="hibernate.connection.password" value="****" />
<property name="hibernate.hbm2ddl.auto" value="update" />
<property name="hibernate.event.merge.entity_copy_observer"
value="allow" />
<property name="c3p0.acquire_increment" value="1" />
<property name="c3p0.idle_test_period" value="100" />
<property name="c3p0.max_size" value="100" />
<property name="c3p0.max_statements" value="0" />
<property name="c3p0.min_size" value="10" />
<property name="c3p0.timeout" value="100" />
<property name="hibernate.c3p0.preferredTestQuery" value="SELECT 1" />
</properties>
</persistence-unit>
Someone is having the same problem or knows a solution?
Thanks in advance!!!

Try with the following JDBC url
jdbc:mysql://localhost:3306/poc
poc is schema name

Tomcat 8 hangs on startup

I'm trying to start my Tomcat server on Eclipse but it always hangs on this line on the logs
14:44:52.467 INFO o.s.o.j.LocalContainerEntityManagerFactoryBean - Building JPA container EntityManagerFactory for persistence unit 'default'
I've even set the timeout to 999 seconds and still will timeout.
I'm trying to start my Spring webapp using Maven.
So I may pinpoint the cause of the hang, what is happening during Building JPA container EntityManagerFactory for persistence unit 'default'? And why is it hanging there?
Here is my context.xml in Tomcat
<Resource name="jdbc/default" auth="Container" type="javax.sql.DataSource"
maxActive="-1" maxIdle="-1" maxWait="-1" autoReconnect="true"
username="example" password="example" driverClassName="com.mysql.jdbc.Driver"
spring.datasource.testOnBorrow="true"
spring.datasource.validationQuery="SELECT 1"
url="jdbc:mysql://example:1106/example" />
<Resource name="jdbc/default_gathering" auth="Container" type="javax.sql.DataSource"
maxActive="-1" maxIdle="-1" maxWait="-1" autoReconnect="true"
username="example" password="example" driverClassName="com.mysql.jdbc.Driver"
spring.datasource.testOnBorrow="true"
spring.datasource.validationQuery="SELECT 1"
url="jdbc:mysql://example:1106/admin" />
persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<non-jta-data-source>java:/comp/env/jdbc/default</non-jta-data-source>
<properties>
<property name="hibernate.cache.provider_class" value="org.hibernate.cache.HashtableCacheProvider" />
<property name="hibernate.format_sql" value="true" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.jdbc.batch_size" value="20" />
<property name="hibernate.cache.use_query_cache" value="false" />
<property name="hibernate.hbm2ddl.auto" value="update" />
<property name="hibernate.cache.use_second_level_cache"
value="false" />
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
<property name="jadira.usertype.autoRegisterUserTypes"
value="true" />
</properties>
</persistence-unit>
<persistence-unit name="default_gathering" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<non-jta-data-source>java:/comp/env/jdbc/default_gathering</non-jta-data-source>
<properties>
<property name="hibernate.cache.provider_class" value="org.hibernate.cache.HashtableCacheProvider" />
<property name="hibernate.format_sql" value="true" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.jdbc.batch_size" value="20" />
<property name="hibernate.cache.use_query_cache" value="false" />
<property name="hibernate.hbm2ddl.auto" value="update" />
<property name="hibernate.cache.use_second_level_cache"
value="false" />
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
<property name="jadira.usertype.autoRegisterUserTypes"
value="true" />
</properties>
</persistence-unit>
dispatcher-servlet.xml
<jee:jndi-lookup id="defaultDS" jndi-name="jdbc/default"
expected-type="javax.sql.DataSource" />
<jee:jndi-lookup id="defaultDS_gathering"
jndi-name="jdbc/default_gathering" expected-type="javax.sql.DataSource" />
<!-- Session Factory Declaration -->
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="defaultDS" />
<property name="persistenceUnitName" value="default" />
<property name="packagesToScan" value="com.default.*" />
</bean>
<bean id="entityManagerFactoryDataGathering"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="defaultDS_gathering" />
<property name="persistenceUnitName" value="default_gathering" />
<property name="packagesToScan" value="com.default.*" />
</bean>
<tx:annotation-driven />
<!-- Transaction Manager is defined -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<bean id="transactionManagerDataGathering" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactoryDataGathering" />
</bean>

Hibernate connections strange behavior

We are making a web application where we are using PayPal for the users to make a subscription but we are having some problems. When we are creating accounts, logging in and doing various requests we have no problems but when we are making 4-7 simultaneous payments our connection pool is not behaving properly.
This is an image of the number of connections. You can see the number of connections spikes after a few payments. When we reset the server it drops down. The last time where the connections are high, you can see what's happening when the server gets to take care of the connection itself -
as you can see it takes hours to drop connections.
This is our persistence.xml:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="up2u">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<properties>
<property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/up2u_user?autoReconnect=true&useUnicode=yes&characterEncoding=UTF-8" />
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.connection.username" value="up2u_user2"/>
<property name="hibernate.connection.password" value="e2f2c2ac87"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.temp.use_jdbc_metadata_defaults" value="true"/>
<!-- Connectionpool-->
<property name="hibernate.connection.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider" />
<property name="hibernate.c3p0.max_size" value="200" />
<property name="hibernate.c3p0.min_size" value="10" />
<property name="hibernate.c3p0.max_statements" value="400" />
<property name="hibernate.c3p0.acquireIncrement" value="10"/>
<property name="hibernate.c3p0.acquireRetryAttempts" value="3"/>
<property name="hibernate.c3p0.acquireRetryDelay" value="100"/>
<property name="hibernate.c3p0.checkoutTimeout" value="300" />
<property name="hibernate.c3p0.timeout" value="300" />
<property name="hibernate.c3p0.idle_test_period" value="300" />
<property name="hibernate.c3p0.idleConnectionTestPeriod" value="300" />
<property name="hibernate.c3p0.maxConnectionAge" value="300" />
<property name="hibernate.c3p0.maxStatementsPerConnection" value="2" />
<property name="hibernate.c3p0.testConnectionOnCheckin" value="true"/>
</properties>
</persistence-unit>
</persistence>
Why is the number connections not dropping when doing payments? The CPU and memory aren't working significantly more when doing payments and I can see nothing more than the connections building and a few more packets/second in firewall throughput.

Externalize dynamic properties in persistence.xml

We are using the bellow properties in our persistence.xml file.
<properties>
<property name="javax.persistence.jdbc.driver" value="oracle.jdbc.driver.OracleDriver" />
<property name="javax.persistence.jdbc.dialect" value="org.hibernate.dialect.OracleDialect" />
<property name="javax.persistence.jdbc.url" value="jdbc:oracle:thin:#XYZDB01:78111:TATAD1" />
<property name="javax.persistence.jdbc.user" value="admin" />
<property name="javax.persistence.jdbc.password" value="admin#123" />
<property name="javax.persistence.jdbc.Schema" value="CSMVC" />
</properties>
But I want to externalize the dynamic properties from persistence.xml something like bellow.
<properties>
<property name="javax.persistence.jdbc.driver" value="${db.driver}" />
<property name="javax.persistence.jdbc.dialect" value="${db.dialect}" />
<property name="javax.persistence.jdbc.url" value="${db.url}" />
<property name="javax.persistence.jdbc.user" value="${db.user}" />
<property name="javax.persistence.jdbc.password" value="${db.password}" />
<property name="javax.persistence.jdbc.Schema" value="${db.schema}" />
</properties>
Note: We are using openJpa as the JPA provider.

Normally, you would define your datasource in your container and have JPA look it up via JNDI. Are you running JPA in Spring/TomEE/Tomcat/Wildfly/Liberty or anything else?

Persistance.xml vs DispatcherServlet

I am using JPA 2.0, Hibernate 3 Annotation Version, the problem is that i am confusing in Persistence.xml & DispatcherServlet
My persistence.xml file contains:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="Hello" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>models.student</class>
<properties>
<property name="hibernate.show_sql" value="true" />
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://127.0.0.1:3306/test"/>
<property name="javax.persistence.jdbc.user" value="root" />
<property name="javax.persistence.jdbc.password" value="admin" />
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLInnoDBDialect"/>
</properties>
</persistence-unit>
</persistence>
In my dispatcher servlet file I have following Beans:
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/test" />
<property name="username" value="root" />
<property name="password" value="admin" />
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitName" value="Hello" />
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="databasePlatform" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
<property name="showSql" value="true" />
<property name="generateDdl" value="true" />
</bean>
</property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
Question is: why do we need to put all properties (DriverClassName, URL, UserName, Password) in both persistence.xml and in DataSource bean in DispatcherServlet?
I am learning and it is confusing me, please help.

Actually you have double configuration here.
You need either persistence.xml or bean definitions.
Take a look here