iperf server side does not quit

Does it normal that the iperf in the server side does not quit even when the iperf on the client side exits the function after finishes?

to explain the issue more in detail, I am running iperf on one BBB as a server and on the other BBB as a client to measure the throughput.

TX Client-side: sudo iperf -c -u -b 400k -l 800 -p 10001 -t 100

RX Server-side: sudo iperf -u -l 800 -s -i3 -B -p 10001

after printing the result, the client iperf quits its function but the server stays in it.

Off-hand, I'd expect a server to remain running... Waiting for the
/next/ client to connect.

iPerf3 servers will only allow one iPerf connection at a time. Multiple
tests at the same time is not supported. If a test is in progress, the
following message is displayed: "iperf3: error - the server is busy running
a test. try again later"

-s, --server Run iPerf in server mode. (This will only allow one iperf
connection at a time)

  One connection at a time, but nothing says only one connection per