This is possibly related to the way the queue between StreamIterationTail and 
Head is currently implemented.
I think this part is a bit prone to records loss when things get wacky and 
backpressure kicks in (but at least it avoids deadlocks, right?).

I don’t have the time availability to look into the code right now but I am 
going to focus on a progress/loops by September, hopefully with a FLIP, which 
solves that part as well.

If  this is urgent, please go ahead and check this now, I think that queue 
timeouts cause this...

Paris

PS: on my yet incomplete PR (I know I know) I basically disabled queue polling 
timeouts since the checkpoint overhead on the StreamIterationHead almost always 
led to record loss.
https://github.com/apache/flink/pull/1668

On 20 Jul 2016, at 11:57, Maximilian Michels 
<m...@apache.org<mailto:m...@apache.org>> wrote:

CC Gyula and Paris in case they might want to help out.

On Tue, Jul 19, 2016 at 11:43 AM, Biplob Biswas
<revolutioni...@gmail.com<mailto:revolutioni...@gmail.com>> wrote:
Hi Ufuk,

Thanks for the update, is there any known way to fix this issue? Any
workaround that you know of, which I can try?



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