[ORCHESTRA-32] Hot-restart of Tomcat causes NullPointerException while deserializing saved http-session

• Type: Bug
• Status: Reopened
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.2
• Component/s: Conversation
• Assignee: Simon Kitching
• Reporter: Simon Kitching
• Created: 13/Nov/08 10:34
• Updated: 14/Dec/09 22:33

Description

Tomcat displays this message on restart:

SCHWERWIEGEND: Exception loading sessions from persistent storage
java.lang.NullPointerException
at java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:881)
at org.apache.catalina.session.StandardSession.readObject(StandardSession.java:1445)

The problem is that the orchestra ConversationManager class has a readResolve method that returns null, intending that the object just gets created "on demand" later. However Tomcat tries to put the deserialized object into its session - and null objects are not permitted in an HttpSession.