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: > Hi, > > 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 > disappear. > > I'm using Flink 1.8.1. > > Did anyone experience something like this before? > > Jan > >
