I am trying to deploy the jetty server but getting the below exception.

Exception in thread "C3P0PooledConnectionPoolManager[identityToken->15fcjvo9g1p8tnnp7gdgkr|11574592]-AdminTaskTimer" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$AsyncTestIdleResourceTask
at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
Caused by: java.lang.ClassNotFoundException: com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:487)
at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:428)
... 5 more
Exception in thread "C3P0PooledConnectionPoolManager[identityToken->15fcjvo9g1p8tnnp7gdgkr|2b4727e4]-AdminTaskTimer" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$AsyncTestIdleResourceTask
at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
Exception in thread "C3P0PooledConnectionPoolManager[identityToken->15fcjvo9g1p8tnnp7gdgkr|457d81d8]-AdminTaskTimer" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$AsyncTestIdleResourceTask
at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
23 May 2016 14:00:52 INFO [DBConstantsExecutor [0

Also, I cannot close my SessionFactory as my data is fed even before the application runs and I don't want to loose my data.
Is there any other method?

You have a class loading issue. This can be caused if:

1. You don't have c3p0 lib in your classpath.
2. You have multiple versions on c3p0, so the ClassLoader sometimes loads a class from one version and other class from some other version.

None of the above is my case :(