RE: State Processor API - VoidNamespaceSerializer must be compatible with the old namespace serializer LongSerializer

Schwalbe Matthias Thu, 27 Oct 2022 00:17:05 -0700

Hi Filip, Hi Tsu-Li,

@Tsu-Li: long time not seen 😊 (it is time for an on-site FlinkForward in Berlin 
again next year 😊 )


Considering Tsu-Li’s proposal, there is a restriction, at the time being you 
can only create a HybridSource from other sources that have exactly the same 
type.
This is not always feasible given that Flip-27 sources have no means of 
projecting to a specific type within the source.
E.g. a flat-file HDFS source of String won’t match with a on-line Kafka source 
of some AVRO formatted type … to get this working is really tricky.

There is another idea that comes to mind (i.e. not verified / tested):

  *   Implement a MultipleInputOperator with InputSelectable (example see [1])
  *   Always select the bounded input until that one is finished,
  *   The other input(s) will backpressure until getting selected

A third idea, that worked before the existence of MultipleInputOperator was to

  *   Union the streams and buffer incoming records in keyed state (e.g. map 
state of timestamp -> List[event]), and
  *   By means of timers yield them only once the watermark passes by the 
stored timestamp
  *   State backend needs to be RocksDB for this because you can iterate 
MapState by Key-order (= timestamp), this does not work well for the other 
state backends
     *   @Tsu-Li: I remember well when you demonstrated this trick on the 
conference a couple of years ago
  *   The problem with this is, that you collect lots of state because of 
watermark-skew among the two input stream
  *   This can be remedied by restricting watermark-skew in job configuration 
[2]

@Filip: feel free to get back to us for help with getting this set-up …

Sincere grettings


Thias



[1] 
org.apache.flink.streaming.api.graph.StreamGraphGeneratorBatchExecutionTest.InputSelectableMultipleInputOperator
[2] 
https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/event-time/generating_watermarks/#watermark-alignment-_beta_

From: Tzu-Li (Gordon) Tai <tzuli...@apache.org>
Sent: Wednesday, October 26, 2022 6:59 PM
To: Filip Karnicki <filip.karni...@gmail.com>
Cc: Schwalbe Matthias <matthias.schwa...@viseca.ch>; user 
<user@flink.apache.org>
Subject: Re: State Processor API - VoidNamespaceSerializer must be compatible 
with the old namespace serializer LongSerializer

⚠EXTERNAL MESSAGE – CAUTION: Think Before You Click ⚠


Hi Filip,

I think what you are seeing is expected. The State Processor API was intended 
to allow access only to commonly used user-facing state structures, while 
Stateful Functions uses quite a bit of Flink internal features, including for 
its state maintenance.
The list state in question in StateFun's FunctionGroupOperator is an internal 
kind of state normally used in the context of Flink window states that are 
namespaced. Normal user-facing list states are not namespaced.

Just curious, which specific state in FunctionGroupOperator are you trying to 
transform? I assume all other internal state in FunctionGroupOperator you want 
to remain untouched, and only wish to carry them over to be included in the 
transformed savepoint?

Thanks,
Gordon


On Wed, Oct 26, 2022 at 3:50 AM Filip Karnicki 
<filip.karni...@gmail.com<mailto:filip.karni...@gmail.com>> wrote:
Hi Thias

Thank you for your reply. I can re-create a simplified use case at home and 
stick it on github if you think it will help.

What I'm trying to access is pretty internal to Flink Stateful Functions. It 
seems that a custom operator 
(https://github.com/apache/flink-statefun/blob/09a5cba521e9f994896c746ec9f8cc6479403612/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/functions/FunctionGroupOperator.java#L188)
 is accessing a KeyedStateBackend and creating an InternalListState, which I'm 
not sure I'll be able to get my hands on using the State Processor API.

The only reason why I need to get my hands on all the states from this Stateful 
Functions operator is because later I (think I) have to use 
.removeOperator(uid) on a savepoint and replace it .withOperator(uid, 
myTransformation) in order to transform my own, non-stateful-functions keyed 
state which also belongs to this operator.

Kind regards
Fil

On Tue, 25 Oct 2022 at 16:24, Schwalbe Matthias 
<matthias.schwa...@viseca.ch<mailto:matthias.schwa...@viseca.ch>> wrote:
Hi Filip,

It looks like, your state primitive is used in the context of Windows:
Keyed state works like this:
·         It uses a cascade of key types to store and retrieve values:
o    The key (set by .keyBy)
o    A namespace (usually a VoidNamespace), unless it is used in context of a 
specific window
o    An optional key of the state primitive (if it is a MapState)

In your case the state primitive is (probably) declared in the context of a 
window and hence when loading the state by means of StateProcessorAPI you also 
need to specify the correct Namespace TypeInformation.
If I am in doubt, how a state primitive is set up, I let the debugger stop in a 
process function and walk up the call stack to find the proper components 
implementing it.

If you share a little more of your code it is much easier to provide specific 
guidance 😊
(e.g. ‘savepoint’ is never used again in your code snippet …)

Sincere greeting

Thias



From: Filip Karnicki <filip.karni...@gmail.com<mailto:filip.karni...@gmail.com>>
Sent: Tuesday, October 25, 2022 10:08 AM
To: user <user@flink.apache.org<mailto:user@flink.apache.org>>
Subject: State Processor API - VoidNamespaceSerializer must be compatible with 
the old namespace serializer LongSerializer

Hi, I'm trying to load a list state using the State Processor API (Flink 1.14.3)

Cluster settings:


state.backend: rocksdb

state.backend.incremental: true

(...)

Code:

val env = ExecutionEnvironment.getExecutionEnvironment
val savepoint = Savepoint.load(env, pathToSavepoint, new 
EmbeddedRocksDBStateBackend(true))

val tpe = new 
MessageTypeInformation(MessageFactoryKey.forType(MessageFactoryType.WITH_PROTOBUF_PAYLOADS,
 null) // using Flink Stateful Functions
val envelopeSerializer: TypeSerializer[Message] = 
tpe.createSerializer(env.getConfig)
val listDescriptor = new ListStateDescriptor[Message]("delayed-message-buffer", 
envelopeSerializer.duplicate)

(...)
override def open(parameters: Configuration): Unit = {
    getRuntimeContext.getListState(listDescriptor) // fails with error [1]
}


Error [1]:

Caused by: java.io.IOException: Failed to restore timer state
            at 
org.apache.flink.state.api.input.KeyedStateInputFormat.open(KeyedStateInputFormat.java:177)
            at 
org.apache.flink.state.api.input.KeyedStateInputFormat.open(KeyedStateInputFormat.java:64)
            at 
org.apache.flink.runtime.operators.DataSourceTask.invoke(DataSourceTask.java:183)
            at 
org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:958)
            at 
org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:937)
            at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:766)
            at org.apache.flink.runtime.taskmanager.Task.run(Task.java:575)
            at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.RuntimeException: Error while getting state
            at 
org.apache.flink.runtime.state.DefaultKeyedStateStore.getListState(DefaultKeyedStateStore.java:74)
            at 
org.apache.flink.state.api.runtime.SavepointRuntimeContext.getListState(SavepointRuntimeContext.java:213)
            at 
x.x.x.x.x.myModule.StateReader$$anon$1.open(StateReader.scala:527)
            at 
org.apache.flink.api.common.functions.util.FunctionUtils.openFunction(FunctionUtils.java:34)
            at 
org.apache.flink.state.api.input.operator.StateReaderOperator.open(StateReaderOperator.java:106)
            at 
org.apache.flink.state.api.input.operator.KeyedStateReaderOperator.open(KeyedStateReaderOperator.java:66)
            at 
org.apache.flink.state.api.input.KeyedStateInputFormat.open(KeyedStateInputFormat.java:174)
            ... 7 more
Caused by: org.apache.flink.util.StateMigrationException: The new namespace 
serializer 
(org.apache.flink.runtime.state.VoidNamespaceSerializer@2806d6da<mailto:org.apache.flink.runtime.state.VoidNamespaceSerializer@2806d6da>)
 must be compatible with the old namespace serializer 
(org.apache.flink.api.common.typeutils.base.LongSerializer@52b06bef<mailto:org.apache.flink.api.common.typeutils.base.LongSerializer@52b06bef>).
            at 
org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend.updateRestoredStateMetaInfo(RocksDBKeyedStateBackend.java:685)
            at 
org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend.tryRegisterKvStateInformation(RocksDBKeyedStateBackend.java:624)
            at 
org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend.createInternalState(RocksDBKeyedStateBackend.java:837)
            at 
org.apache.flink.runtime.state.KeyedStateFactory.createInternalState(KeyedStateFactory.java:47)
            at 
org.apache.flink.runtime.state.ttl.TtlStateFactory.createStateAndWrapWithTtlIfEnabled(TtlStateFactory.java:73)
            at 
org.apache.flink.runtime.state.AbstractKeyedStateBackend.getOrCreateKeyedState(AbstractKeyedStateBackend.java:302)
            at 
org.apache.flink.runtime.state.AbstractKeyedStateBackend.getPartitionedState(AbstractKeyedStateBackend.java:353)
            at 
org.apache.flink.runtime.state.DefaultKeyedStateStore.getPartitionedState(DefaultKeyedStateStore.java:115)
            at 
org.apache.flink.runtime.state.DefaultKeyedStateStore.getListState(DefaultKeyedStateStore.java:71)
            ... 13 more



It seems that DefaultKeyedStateStore always wants to use 
VoidNamespaceSerializer.INSTANCE despite my state being created with a 
LongSerializer namespace serializer.

Is there anything anyone can immediately see me doing wrong?

Thank you
Fil
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e-Mail-Nachrichten nicht gewährleistet werden kann, übernehmen wir keine 
Haftung für die Gewährung der Vertraulichkeit und Unversehrtheit dieser 
Mitteilung. Bei irrtümlicher Zustellung bitten wir Sie um Benachrichtigung per 
e-Mail und um Löschung dieser Nachricht sowie eventueller Anhänge. Jegliche 
unberechtigte Verwendung oder Verbreitung dieser Informationen ist streng 
verboten.

This message is intended only for the named recipient and may contain 
confidential or privileged information. As the confidentiality of email 
communication cannot be guaranteed, we do not accept any responsibility for the 
confidentiality and the intactness of this message. If you have received it in 
error, please advise the sender by return e-mail and delete this message and 
any attachments. Any unauthorised use or dissemination of this information is 
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RE: State Processor API - VoidNamespaceSerializer must be compatible with the old namespace serializer LongSerializer

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