I can check
gstack, but just because I see the listener threads on the
recv call does not mean that call is not returning. One other thing I thought was to do something like:
netstat -lupe | grep <PROCESS_PID>
to check the inodes of the sockets listening via udp. Then possibly try watching (
watch command) what
/proc/net/udp says about the receive and transmit queues of those inodes. I'm not sure if this is a good way to diagnose this, however. Trying to listen to the same multicast groups to check for data coming in is also not really a guarantee that the process in question is receiving it.
What are some other ways or things I could probe or try?