If we're going to open sockets, we need to make the binding configurable so admins can lock down what is used. 127.0.0.1:0 is fine as a default though.
Haha, I started off as opposed to using stdio, but now feel oddly supportive of it. Not sure why.
In any case, even if we use sockets for the inter-process messaging traffic, these thread dumps are going to go to the PM via stdout/ManagedProcess$OutputStreamHandler. So we need to decide what to do with them. Convert them to log messages in the PM log, a la the above? Dump the directly to PM's stdout? (I'm checking if that will actually just result in log messages in the PM log file.) Maintain a file per managed process?