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https://issues.apache.org/jira/browse/FLINK-4149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15362717#comment-15362717
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ASF GitHub Bot commented on FLINK-4149:
---------------------------------------
GitHub user aljoscha opened a pull request:
https://github.com/apache/flink/pull/2202
[FLINK-4149] Fix Serialization of NFA in AbstractKeyedCEPPatternOperator
NFA is Serializable and has readObject()/writeObject() methods. In
AbstractKeyedCEPPatternOperator a KryoSerializer was used as the
TypeSerializer for the ValueState that holds NFA instances. Kryo does
not call readObject()/writeObject() therefore the state of the NFA was
invalid after deserialization.
This change adds a new TypeSerializer for NFA that uses
Java Serialization. In the long run it will be better to get rid of the
readObject()/writeObject() methods and instead efficiently serialize
using a specialized TypeSerializer.
This also adds a test that verifies that checkpoint/restore work as
expected.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/aljoscha/flink cep/fix-serialization
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/2202.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #2202
----
commit ba1deb8cae7223f3ca9def1b09b311e7d7889a8a
Author: Aljoscha Krettek <aljoscha.kret...@gmail.com>
Date: 2016-07-05T15:56:49Z
Replace StreamEvent by StreamRecord in CEP Tests
commit 19aaa005e0389b512a563cf28e82d8ad07c4a194
Author: Aljoscha Krettek <aljoscha.kret...@gmail.com>
Date: 2016-07-05T15:58:45Z
[FLINK-4149] Fix Serialization of NFA in AbstractKeyedCEPPatternOperator
NFA is Serializable and has readObject()/writeObject() methods. In
AbstractKeyedCEPPatternOperator a KryoSerializer was used as the
TypeSerializer for the ValueState that holds NFA instances. Kryo does
not call readObject()/writeObject() therefore the state of the NFA was
invalid after deserialization.
This change adds a new TypeSerializer for NFA that uses
Java Serialization. In the long run it will be better to get rid of the
readObject()/writeObject() methods and instead efficiently serialize
using a specialized TypeSerializer.
----
> Fix Serialization of NFA in AbstractKeyedCEPPatternOperator
> -----------------------------------------------------------
>
> Key: FLINK-4149
> URL: https://issues.apache.org/jira/browse/FLINK-4149
> Project: Flink
> Issue Type: Bug
> Components: CEP
> Affects Versions: 1.0.0, 1.1.0, 1.0.1, 1.0.2, 1.0.3
> Reporter: Aljoscha Krettek
> Assignee: Aljoscha Krettek
> Priority: Blocker
> Fix For: 1.1.0
>
>
> 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:
> {code}
> new ValueStateDescriptor<NFA<IN>>(
> NFA_OPERATOR_STATE_NAME,
> new KryoSerializer<NFA<IN>>((Class<NFA<IN>>) (Class<?>) NFA.class,
> getExecutionConfig()),
> null)
> {code}
> It seems Kryo does not invoke {{readObject}}/{{writeObject}}. We probably
> need a custom {{TypeSerializer}} for {{NFA}} to solve the problem.
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