[FLINK-4149] Fix Serialization of NFA in AbstractKeyedCEPPatternOperator

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0
• Fix Version/s: 1.1.0
• Component/s: Library / CEP
• Assignee: Aljoscha Krettek
• Reporter: Aljoscha Krettek
• Created: 04/Jul/16 14:54
• Updated: 18/Apr/17 12:37
• Resolved: 18/Jul/16 12:08

Description

A job that uses CEP fails upon restore with a NullPointerException in NFA.process(). The reason seems to be that field computationStates is null. This field is transient and read in a custom readObject() method.

In AbstractKeyedCEPPatternOperator this snipped is used to construct a StateDescriptor for an NFA state:

new ValueStateDescriptor<NFA<IN>>(
    NFA_OPERATOR_STATE_NAME,
    new KryoSerializer<NFA<IN>>((Class<NFA<IN>>) (Class<?>) NFA.class, getExecutionConfig()),
    null)

It seems Kryo does not invoke readObject/writeObject. We probably need a custom TypeSerializer for NFA to solve the problem.

Issue Links

• links to: GitHub Pull Request #2202