Process using TCP connections are not restored on docker container restoration

Hi,

Case:
I am using two Alpine containers and running Iperf application inside them. One container runs Iperf as server and other container runs Iperf as client. I can checkpoint and restore the server. But on restoration, I don’t see any Iperf process running in the container.
Question:
Does docker checkpointing clears any open sockets? Or, is there any way to restore the Iperf server. I read docker uses CRIU for checkpointing and CRIU allows to checkpoint open sockets using --tcp-establish. So, can docker also allow checkpointing and restoring processes, e.g. iperf, that uses open TCP sockets?

System and software version
I am using Docker version 1.13.1, build 092cba3 and criu Version: 3.5. My OS is Ubuntu 17.04. Here is the output of uname -a

Linux o19 4.10.0-19-generic #21-Ubuntu SMP Thu Apr 6 17:04:57 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Thanks.