[jira] [Created] (FLINK-6472) BoundedOutOfOrdernessTimestampExtractor does not bound out of orderliness

["Elias Levy (JIRA)" <ji...@apache.org>]

Elias Levy created FLINK-6472:
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             Summary: 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: Streaming
    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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