Hi
>From the exception `No key set. This method should not be called outside of
a keyed context.` it means that the key current passed in is null. In my
opinion, it's something wrong here if there will throw an exception when no
data arrive. could you please share the whole stack and a minimal
reproducible job for this issue?
Best,
Congxian
Salva Alcántara <salcantara...@gmail.com> 于2019年12月1日周日 下午3:01写道：
> Given:
>
>
> ```scala
> class MyOperator extends KeyedCoProcessFunction[String, ModelDef, Data,
> Prediction]
> with CheckpointedFunction {
>
> // To hold loaded models
> @transient private var models: HashMap[(String, String), Model] = _
>
> // For serialization purposes
> @transient private var modelsBytes: MapState[(String, String),
> Array[Bytes]] = _
>
> ...
>
> override def snapshotState(context: FunctionSnapshotContext): Unit = {
> modelsBytes.clear() // This raises an exception when there is no
> active key set
> for ((k, model) <- models) {
> modelsBytes.put(k, model.toBytes(v))
> }
> }
>
> override def initializeState(context: FunctionInitializationContext):
> Unit = {
> modelsBytes = context.getKeyedStateStore.getMapState[String, String](
> new MapStateDescriptor("modelsBytes", classOf[String],
> classOf[String])
> )
>
> if (context.isRestored) {
> // restore models from modelsBytes
> }
> }
>
> }
> ```
>
> It happens that `modelsBytes.clear()` raises an exception when there is no
> active key. This happens when I start the application from scratch without
> any data on the input streams. So, when the time for a checkpoint comes, I
> get this error:
>
> `java.lang.NullPointerException: No key set. This method should not be
> called outside of a keyed context.`
>
> However, when the input stream contains data, checkpoints work just fine.
> I am a bit confused about this because `snapshotState` does not provide a
> keyed context (contrary to `processElement1` and `processElement2`, where
> the current key is accessible by doing `ctx.getCurrentKey`) so it seems to
> me that the calls to `clear` and `put` within `snapshotState` should fail
> always since they're supposed to work only within a keyed context. Can
> anyone clarify if this is the expected behaviour actually?
>
>
