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https://issues.apache.org/jira/browse/FLINK-6472?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16002416#comment-16002416
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Aljoscha Krettek commented on FLINK-6472:
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I think we might have to un-deprecate {{TimestampExtractor}}
https://github.com/apache/flink/blob/5aa93a270a87b5a965e5c37c5c8bd6e6208b09b7/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/TimestampExtractor.java#L43-L43.
Originally, this was the only available interface for timestamp/watermark
extraction and allowed both periodic and punctuated watermarks.
Alternatively, we could think about letting an extractor implement both
{{AssignerWithPeriodicWatermarks}} and {{AssignerWithPunctuatedWatermarks}} and
have a unified operator that can handle that case (This would replace
{{TimestampsAndPunctuatedWatermarksOperator}} and
{{TimestampsAndPeriodicWatermarksOperator}}).
What do you think?
> BoundedOutOfOrdernessTimestampExtractor does not bound out of orderliness
> -------------------------------------------------------------------------
>
> Key: FLINK-6472
> URL: https://issues.apache.org/jira/browse/FLINK-6472
> Project: Flink
> Issue Type: Bug
> Components: DataStream API
> Affects Versions: 1.3.0
> Reporter: Elias Levy
>
> {{BoundedOutOfOrdernessTimestampExtractor}} attempts to emit watermarks that
> lag behind the largest observed timestamp by a configurable time delta. It
> fails to so in some circumstances.
> The class extends {{AssignerWithPeriodicWatermarks}}, which generates
> watermarks in periodic intervals. The timer for this intervals is a
> processing time timer.
> In circumstances where there is a rush of events (restarting Flink, unpausing
> an upstream producer, loading events from a file, etc), many events with
> timestamps much larger that what the configured bound would normally allow
> will be sent downstream without a watermark. This can have negative effects
> downstream, as operators may be buffering the events waiting for a watermark
> to process them, thus leading the memory growth and possible out-of-memory
> conditions.
> It is probably best to have a bounded out of orderliness extractor that is
> based on the punctuated timestamp extractor, so we can ensure that watermarks
> are generated in a timely fashion in event time, with the addition of process
> time timer to generate a watermark if there has been a lull in events, thus
> also bounding the delay of generating a watermark in processing time.
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