Python with tcpdump in a subprocess: how to close subprocess properly?

Instead of p.kill(), you can use p.send_signal(subprocess.signal.SIGTERM) to send a terminate signal rather than a kill (p.terminate() does the same).

The Popen docs describe the send_signal() command. The documentation on signals is a bit weak, but a dir(subprocess.signal) will list all the signals you may send to the process, but terminate should allow it some time to clean up.

Found working solution:
I've changed p.kill() to p.terminate().
After this change the subprocess is "properly" finished (output of tcpdump subprocess with statistics available in console) and output .pcap file not damaged.