Github user NicoK commented on the issue:
With the recent update of the netty version in flink-shaded (see
most of this PR is indirectly included. However, I probably need to fall back
to the original code creating a copy at least for the fallback non-credit based
paths due to the original problem.
Additionally, since the introduction of the credit-based flow control we
should not use too much memory on the receiver side anymore: memory size in the
range of once in our buffers, at most one (or two depending on the above) more
copies in netty temporarily.
Ultimately, we could go one step further of decoding directly to our
buffers here, but that is not covered by this PR and will only work with
credit-based flow control.