[ https://issues.apache.org/jira/browse/FLINK-13798?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
zhijiang updated FLINK-13798: ----------------------------- Description: As we know, the watermark could be emitted to downstream only when the stream status is active. For the downstream task we already have the component of StatusWatermarkValve in StreamInputProcessor to handle this logic. But for the source task the current implementation of this logic seems a bit tricky. There are two scenarios for the source case: * In the source WatermarkContext, it would toggle the status as active while collecting/emitting and the status is checked in RecordWriterOutput. If the watermark is triggered by timer for AutomaticWatermarkContext, the timer task would check the status before emitting watermark. * TimestampsAndPeriodicWatermarksOperator: The watermark is triggered by timer, but it still relies on RecordWriterOutput to check the status before emitting. So the check logic in RecordWriterOutput only makes sense for the last scenario, and seems redundant for the first scenario. Even worse, this logic is RecordWriterOutput would bring cycle dependency with StreamStatusMaintainer, which is a blocker for the following work of integrating source processing on runtime side. To solve above issues, the basic idea is to refactor this check logic in upper layer instead of current low level RecordWriterOutput. The solution is migrating the check logic from RecordWriterOutput to TimestampsAndPeriodicWatermarksOperator. was: As we know, the watermark could be emitted to downstream only when the stream status is active. For the downstream task we already have the component of StatusWatermarkValve in StreamInputProcessor to handle this logic. But for the source task the current implementation of this logic seems a bit tricky. There are two scenarios for the source case: * In the source WatermarkContext, it would toggle the status as active while collecting/emitting and the status is checked in the RecordWriterOutput. If the watermark is triggered by timer for AutomaticWatermarkContext, the timer task would check the status before emitting watermark. * TimestampsAndPeriodicWatermarksOperator: The watermark is triggered by timer. But it relies on RecordWriterOutput to check the status before emitting. So we can see that the check logic in RecordWriterOutput only makes sense for the last scenario, and seems redundant for the first scenario. Even worse, the logic is RecordWriterOutput would bring cycle dependency with StreamStatusMaintainer, which is a blocker for the following work of integrating source processing on runtime side. To solve above issues, the basic idea is to make this check logic in upper layer instead of current low level RecordWriterOutput. The solution is that we could migrate the checking logic from RecordWriterOutput to TimestampsAndPeriodicWatermarksOperator. And the toggling active action could be removed in AutomaticWatermarkContext while emitting records. > Refactor the process of checking stream status while emitting watermark in > source > --------------------------------------------------------------------------------- > > Key: FLINK-13798 > URL: https://issues.apache.org/jira/browse/FLINK-13798 > Project: Flink > Issue Type: Sub-task > Components: Runtime / Task > Reporter: zhijiang > Assignee: zhijiang > Priority: Minor > > As we know, the watermark could be emitted to downstream only when the stream > status is active. For the downstream task we already have the component of > StatusWatermarkValve in StreamInputProcessor to handle this logic. But for > the source task the current implementation of this logic seems a bit tricky. > There are two scenarios for the source case: > * In the source WatermarkContext, it would toggle the status as active while > collecting/emitting and the status is checked in RecordWriterOutput. If the > watermark is triggered by timer for AutomaticWatermarkContext, the timer task > would check the status before emitting watermark. > * TimestampsAndPeriodicWatermarksOperator: The watermark is triggered by > timer, but it still relies on RecordWriterOutput to check the status before > emitting. > So the check logic in RecordWriterOutput only makes sense for the last > scenario, and seems redundant for the first scenario. > Even worse, this logic is RecordWriterOutput would bring cycle dependency > with StreamStatusMaintainer, which is a blocker for the following work of > integrating source processing on runtime side. > To solve above issues, the basic idea is to refactor this check logic in > upper layer instead of current low level RecordWriterOutput. The solution is > migrating the check logic from RecordWriterOutput to > TimestampsAndPeriodicWatermarksOperator. -- This message was sent by Atlassian Jira (v8.3.2#803003)