I remember an issue regarding the watermark fetch request from the WebUI exceeding some HTTP size limit, since it tries to fetch all watermarks at once, and the format of this request isn't exactly efficient.

Querying metrics for individual operators still works since the request is small enough.

Not sure whether we ever fixed that.

On 15/08/2019 12:01, Jan Lukavský wrote:

Thomas, thanks for confirming this. I have noticed, that in 1.9 the WebUI has been reworked a lot, does anyone know if this is still an issue? I currently cannot easily try 1.9, so I cannot confirm or disprove that.


On 8/14/19 6:25 PM, Thomas Weise wrote:
I have also noticed this issue (Flink 1.5, Flink 1.8), and it appears with
higher parallelism.

This can be confusing to the user when watermarks actually work and can be
observed using the metrics.

On Wed, Aug 14, 2019 at 7:36 AM Jan Lukavský <je...@seznam.cz> wrote:


is it possible, that watermarks are sometimes not propagated to WebUI,
although they are internally moving as normal? I see in WebUI every
operator showing "No Watermark", but outputs seem to be propagated to
sink (and there are watermark sensitive operations involved - e.g.
reductions on fixed windows without early emitting). More strangely,
this happens when I increase parallelism above some threshold. If I use
parallelism of N, watermarks are shown, when I increase it above some
number (seems not to be exactly deterministic), watermarks seems to

I'm using Flink 1.8.1.

Did anyone experience something like this before?


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