C3p0 null pointer exception

Lourival Silva · **Joined:** Wed Mar 14, 2007 3:36 pm **Posts:** 2

Hello,
My name is Lourival and I am getting the following error
when I try to start up the Tomcat webserver:

org.hibernate.HibernateException: Could not instantiate C3P0 connection pool
at org.hibernate.connection.C3P0ConnectionProvider.configure(C3P0ConnectionProvider.java:163)
at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:124)
at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:56)
at org.hibernate.cfg.SettingsFactory.createConnectionProvider(SettingsFactory.java:410)
at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:62)
at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2009)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1292)
at br.atech.cos.server.persistencia.hibernate.HibernateUtil.<clinit>(HibernateUtil.java:38)
at br.atech.cos.server.startup.CosStartupServlet.<clinit>(CosStartupServlet.java:31)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1055)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:932)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:3917)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4201)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:809)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:698)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:472)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1122)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:310)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1021)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
at org.apache.catalina.core.StandardService.start(StandardService.java:450)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:709)
at org.apache.catalina.startup.Catalina.start(Catalina.java:551)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
Caused by: java.lang.NullPointerException
at java.util.Hashtable.put(Unknown Source)
at com.mchange.v2.c3p0.DataSources.pooledDataSource(DataSources.java:314)
at org.hibernate.connection.C3P0ConnectionProvider.configure(C3P0ConnectionProvider.java:159) ... 40 more

The c3p0 is configured as showed below:


<property name="hibernate.c3p0.max_size">10</property>
<property name="hibernate.c3p0.min_size">2</property>
<property name="hibernate.c3p0.timeout">5000</property>
<property name="hibernate.c3p0.max_statements">10</property>
<property name="hibernate.c3p0.idle_test_period">3000</property>
<property name="hibernate.c3p0.acquire_increment">2</property>

I am using apache-activemq-4.1.0-incubator, apache-tomcat-5.5.17 and hibernate-3.2.2.ga.

I tracked this problem and what I figured out is that The ActiveMq adds a
org.apache.activeio.journal.active.lockMap property with null value in the
java list properties. The Hibernate reads the properties values about Cp30
defined in the configuration file and adds to the java list properties
after that hibernate calls the Cp30 routines passing the properties list. The
Cp30 is not prepared to receive properties that are not in its properties list
neither read null property values so the exception pops up (see the
Caused by clause at the bottom of the exception inserted at
the top of this document).

I'm not so sure If I´ve got a bug or I am doing something wrong.

Could you please help me?

Thanks in advance,
Lourival Silva

swaldman · **Joined:** Tue Jan 06, 2004 8:58 pm **Posts:** 145

Lourival,

Sorry for the delayed response.

c3p0 would have a problem if passed a Properties object that included a null value. The code could easily be modified to defend against this. But I don't understand, I thought Properties objects and Hashtables are unable to accept null values. How did the upstream code manage to create a situation where an iterable key is associated with a null value in a Properties object?

Thanks for your help. I'm afraid I must be missing something basic.

smiles,
Steve

Lourival Silva · **Joined:** Wed Mar 14, 2007 3:36 pm **Posts:** 2

Hi Steve,

I agree with you 100%.

I going to keep diggin up this problem more carefully.
If I find out new evidences or a solution to this problem
I'll let you know.

Thank you very much for your help.
Lourival

smoffatt · **Joined:** Fri Jun 13, 2008 1:00 pm **Posts:** 1

Just ran over this problem in my development, and posted a fix here:

http://code.google.com/p/emcode/wiki/C3 ... rException

Cameron McKenzie · **Posted:** Fri Jun 13, 2008 2:55 pm

Awesome save!

Solution 1

Quote:

Geronimo-specific workaround

There is probably a better way, but we chose to edit geronimo.sh to add the activeio argument, since we have already edited that file to allocate more memory for Geronimo in general. Since we always start Geronimo with the start option, a quick fix for us was to edit the code here:

Solution 2

Quote:

A Better Way

A better way around this is to include a case for null property values in c3p0 itself. It really behooves ActiveIO/ActiveMQ to do the right thing (and apparently this is fixed in a future version, but given the Geronimo mix we have, we aren't interested in upgrading right now).

aupadhye · **Joined:** Thu Feb 02, 2012 9:16 am **Posts:** 1

I was getting the same exception for Glassfish connected to Oracle and could solve it by defining missing properties in c3p0.properties and putting this file in classpath. Basically it expects all the properties from C3P0ConnectionProviderto be defined somewhere., They are following,
private static final java.lang.String C3P0_STYLE_MIN_POOL_SIZE = "c3p0.minPoolSize";
private static final java.lang.String C3P0_STYLE_MAX_POOL_SIZE = "c3p0.maxPoolSize";
private static final java.lang.String C3P0_STYLE_MAX_IDLE_TIME = "c3p0.maxIdleTime";
private static final java.lang.String C3P0_STYLE_MAX_STATEMENTS = "c3p0.maxStatements";
private static final java.lang.String C3P0_STYLE_ACQUIRE_INCREMENT = "c3p0.acquireIncrement";
private static final java.lang.String C3P0_STYLE_IDLE_CONNECTION_TEST_PERIOD = "c3p0.idleConnectionTestPeriod";
private static final java.lang.String C3P0_STYLE_TEST_CONNECTION_ON_CHECKOUT = "c3p0.testConnectionOnCheckout";
private static final java.lang.String C3P0_STYLE_INITIAL_POOL_SIZE = "c3p0.initialPoolSize"

JayasreeVeliyath · **Joined:** Thu Apr 04, 2013 9:03 am **Posts:** 1

I am facing the same issue but, it occurs occasionally.I have multiple applications that are deployed and redeployed.The nullpointer exception does not occur on first deployment.