There's a rare, intermittent failure appearing when using the javac server to compile the JDK, where the javac client fails to connect to the server.

It looks something like this:

Connection attempt failed: Connection refused
Connection attempt failed: Connection refused
Connection attempt failed: Connection refused
Giving up
IOException caught during compilation: Could not connect to server

I'm opening this bug as a infrastructure/build, but it's most likely a langtools issue. But I assume we must handle this together.