With most JDKs lookup the process-id (pid) with jps -m and create the thread dump with
If jstack doesn't come with your JDK you can use
kill -QUIT pid
and look for the thread dump in stdout.
You can also just press CTRL + \ combo on the keyboard while process is running in the console. I prefer the jps + jstack way.
Here is a doc from Red Hat support: https://access.redhat.com/solutions/18178
Also, you can just do ./bin/jconsole.sh in wildfly and inspect threads in JConsole.