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https://issues.apache.org/jira/browse/FLINK-8365?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16333400#comment-16333400
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ASF GitHub Bot commented on FLINK-8365:
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GitHub user bowenli86 opened a pull request:
https://github.com/apache/flink/pull/5326
[FLINK-8365] [State Backend] Relax List type in HeapListState and
HeapKeyedStateBackend
## What is the purpose of the change
`stateTable` in `HeapListState` and
`HeapKeyedStateBackend#createListState()` are both strongly typed to
`ArrayList` right now. Relaxing that to `List` so we can avoid extra copies in
some cases.
Well, the copies in `HeapListState#update()` cannot be completely avoided.
When users pass in an `AbstractList` to `update()` when there's no state
before, it will break and we have to convert it to an `ArrayList` explicitly
## Brief change log
Relax List type in HeapListState and HeapKeyedStateBackend
## Verifying this change
This change is already covered by existing tests, such as
*MemoryStateBackendTest*.
## Does this pull request potentially affect one of the following parts:
none
## Documentation
none
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/bowenli86/flink FLINK-8365
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/5326.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 #5326
----
commit dd2ec2fb3ce53549ba2f0162591658db34f1ac13
Author: Bowen Li <bowenli86@...>
Date: 2018-01-21T05:29:38Z
[FLINK-8365] Relax List type in HeapListState and HeapKeyedStateBackend
commit f9d648fe6d26129a5a126cc860ccc0a58484a193
Author: Bowen Li <bowenli86@...>
Date: 2018-01-21T05:31:33Z
remove unused code
----
> Relax List type in HeapListState and HeapKeyedStateBackend
> ----------------------------------------------------------
>
> Key: FLINK-8365
> URL: https://issues.apache.org/jira/browse/FLINK-8365
> Project: Flink
> Issue Type: Improvement
> Components: State Backends, Checkpointing
> Affects Versions: 1.5.0
> Reporter: Bowen Li
> Assignee: Bowen Li
> Priority: Major
> Fix For: 1.5.0
>
>
> {{stateTable}} in HeapListState and
> {{HeapKeyedStateBackend#createListState()}} are both strongly typed to
> {{ArrayList}} right now.
> As discussed with [~StephanEwen] and [[email protected]] in
> https://github.com/apache/flink/pull/4963, we may want to relax the type to
> {{List}}.
> Problems discovered now:
> 1. That may require changing serializer from {{ArrayListSerializer}} to
> {{ListSerializer}} in the following code, and we need to discuss the pros and
> cons
> {code:java}
> @Override
> public <N, T> InternalListState<N, T> createListState(
> TypeSerializer<N> namespaceSerializer,
> ListStateDescriptor<T> stateDesc) throws Exception {
> // the list state does some manual mapping, because the state
> is typed to the generic
> // 'List' interface, but we want to use an implementation typed
> to ArrayList
> // using a more specialized implementation opens up runtime
> optimizations
> StateTable<K, N, ArrayList<T>> stateTable =
> tryRegisterStateTable(
> stateDesc.getName(),
> stateDesc.getType(),
> namespaceSerializer,
> new
> ArrayListSerializer<T>(stateDesc.getElementSerializer()));
> return new HeapListState<>(stateDesc, stateTable,
> keySerializer, namespaceSerializer);
> }
> {code}
> 2. for non-RocksDBStateBackend (AsyncFileStateBackendTest,
> AsyncMemoryStateBackendTest, FileStateBackendTest, and
> MemoryStateBackendTest), unit tests testListState and
> testListStateAddUpdateAndGet fail
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