GitHub user StefanRRichter opened a pull request:
https://github.com/apache/flink/pull/2512
Partitionable op state
This pull request introduces rescalable non-partitioned operator state as
described in issue [FLINK-4379] and makes following major changes:
# 1) Introducing interfaces `PartitionableStateBackend` and
`SnapshotProvider`
For rescaling purposes, non-partitioned state is now stored in a
`PartitionableStateBackend`, which provides a method to register operator
states under unique names and store state partitions in a list state:
```
<S> ListState<S> getPartitionableState(
String name,
Collection<PartitionableOperatorStateHandle> restoreSnapshots,
TypeSerializer<S> partitionStateSerializer) throws Exception;
```
Notice that a `TypeSerializer` is provided on a per-state basis so that we
can realize backward compatibility if the serialization format changes.
Furthermore, we introduce `SnapshotProvider` which offers a method to
create snapshots:
```
RunnableFuture<S> snapshot(
long checkpointId,
long timestamp,
CheckpointStreamFactory streamFactory) throws Exception;
```
`DefaultPartitionableStateBackend` is an implementation of both,
`PartitionableStateBackend` and `SnapshotProvider`, where the first interface
gives a view that is exposed to user code and the later interface is only used
by the system to trigger snapshots.
Similar to other state backends (e.g. `KeyedStateBackend`), a
`DefaultPartitionableStateBackend` can be created and restored through the
class `AbstractStateBackend`:
```
public DefaultPartitionableStateBackend createPartitionableStateBackend(
Environment env,
String operatorIdentifier)
public DefaultPartitionableStateBackend restorePartitionableStateBackend(
Environment env,
String operatorIdentifier,
Collection<PartitionableOperatorStateHandle> restoreSnapshots)
```
# 2) Interface `PartitionableCheckpointed` as replacement for `Checkpointed`
User code can use rescalable non-partitioned state by implementing the
`PartitionableCheckpointed` interface. This interface is meant to replace the
`Checkpointed` interface, which would become deprecated.
```
void storeOperatorState(long checkpointId, PartitionableStateBackend
backend) throws Exception;
void restoreOperatorState(PartitionableStateBackend backend) throws
Exception;
```
Through the store/restore methods, user code can interact with
`PartitionableStateBackend` and register/restore states as previously explained.
Methods from this interface are invoked in
`StreamTask::performCheckpoint(...)` and `StreamTask::restoreState()`
respectively.
# 3) Interface `StateRepartitioner`
This interface allows implementations of repartitioning strategies the
redistribute non-partitioned state when for changing parallelism. Currently,
there is only one default strategy implemented in `RoundRobinStatePartitioner`,
but in general it is possible to implement different strategies, e.g. a
`StatePartitioner` that distributes the union of all previous states parallel
subtasks to each parallel subtask. This interface is used in
`CheckpointCoordinator::restoreLatestCheckpointedState()`.
TODO: After review, a description of the new features must still be added
to the Flink documentation.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/StefanRRichter/flink partitionable-op-state
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/2512.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 #2512
----
commit d133b948b8a201178e4ad3afa49e715bebf8eb5f
Author: Stefan Richter <s.rich...@data-artisans.com>
Date: 2016-08-31T21:59:27Z
State backend infrastructure to support partitionable op state.
Introducing CheckpointStateHandles as container for all checkpoint related
state handles
tmp repartitioning function wip
commit 7213938be4bd706b57128c49cb24b24450ea1c87
Author: Till Rohrmann <trohrm...@apache.org>
Date: 2016-09-07T16:52:48Z
Add task chain length to TaskState
commit b639c8c62f64f840b95cd6191d7adf514eecddc6
Author: Till Rohrmann <trohrm...@apache.org>
Date: 2016-09-08T21:11:11Z
Forward partitionable operator state to PartitionableCheckpointed operators
commit 090d27f6daa173b43f1c5d2ee19cc661359b925a
Author: Till Rohrmann <trohrm...@apache.org>
Date: 2016-09-08T22:05:13Z
Make Kafka sources re-partitionable by using the partitionable non-keyed
state
Allow Kafka sources to use repartitionable state
Remove CheckpointedAsynchronously from FlinkKafkaConsumerBase
commit bc964d7ad6c1608d8bae0db67efdb70c4c278086
Author: Till Rohrmann <trohrm...@apache.org>
Date: 2016-09-09T13:34:38Z
Make Kafka producer re-partitionable by removing the Checkpointed interface
commit 2366feeff842c3db39625da5a5912a98e83692db
Author: Till Rohrmann <trohrm...@apache.org>
Date: 2016-09-09T17:02:32Z
Fix HeapKeyedStateBackend.restorePartitionedState
commit e71cd8629ac1f195a53749d3303a7acf3cc4e4dd
Author: Stefan Richter <s.rich...@data-artisans.com>
Date: 2016-09-15T16:42:55Z
Partitionable State temporary WIP
commit e84998d2702b9461f59df14c5aa1bb8d7438457a
Author: Stefan Richter <s.rich...@data-artisans.com>
Date: 2016-09-16T12:22:47Z
Introduce partitionable state in savepoint serializer
commit a50629cb8eb876dfcd1af2199e4f4c08bc8562ad
Author: Stefan Richter <s.rich...@data-artisans.com>
Date: 2016-09-16T12:37:34Z
Using known chain length to replace maps with list of known size
commit 2921b478cbc9cadc2c205d8ee66c9f66c11245f1
Author: Stefan Richter <s.rich...@data-artisans.com>
Date: 2016-09-16T17:56:02Z
Added test case for rescaling partitionable state
commit 26b48fedc648715e0ed3e5a4642bede91c86ff02
Author: Stefan Richter <s.rich...@data-artisans.com>
Date: 2016-09-19T10:16:26Z
Code cleanup, minor refinements and documentation
----
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