Bowen Li created FLINK-8365:
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Summary: Consider 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: 1.4.0
Reporter: Bowen Li
Assignee: Bowen Li
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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