prefixAndTail Substream Source has not been materialized in 5000 milliseconds on Windows?

[Christian Schmitt]

Hello,
we are seeing more than often the following on our Windows Nodes:
Substream Source has not been materialized in 5000 milliseconds

The Server is a simple Play! Application which uses the following Flow to Parse Multipart:
https://github.com/playframework/playframework/blob/master/framework/src/play/src/main/scala/play/core/parsers/Multipart.scala#L46

Actually I guess the error needs to happen at the prefixAndTail(1) I guess, but I wasn't sure if maybe the BodyPartParser would fail on Windows if the heap space is too small?
We ran the App on the default Configuration of the JVM so maybe GC kicks in too often for small heaps?

Does somebody have an idea why this might happen?
I never seen that on a Linux machine (however the files that getting uploaded on Linux are way smaller).

We also have a Stacktrace but that of course only points to the timeout.

I'm writing here since the Code was actually borrowed from akka-http and I'm a little bit clueless why that might happen.