We are seeing intermittent failures of the sort,
  "execStatus=Error. Cannot get VM for test: java.net.SocketTimeoutException: Accept timed out"
Each time we see one of these, it has been only in some of the langtools com/sun/javadoc tests which build JavadocTester using the @build tag. The errors are always of this type:

----------messages:(3/117)----------
command: build JavadocTester
reason: User specified action: run build JavadocTester
elapsed time (seconds): 140.828
result: Error. Cannot get VM for test: java.net.SocketTimeoutException: Accept timed out

#section:compile
----------

A typical full jtr file is below. Checking several 100k's of jtr files from almost 200 test runs, these failures occur intermittently exclusively in these tests during @build JavadocTester

    com/sun/javadoc/5093723/T5093723.jtr
    com/sun/javadoc/AccessFrameTitle/AccessFrameTitle.jtr
    com/sun/javadoc/AccessH1/AccessH1.jtr
    com/sun/javadoc/AccessH1/AccessH1.jtr
    com/sun/javadoc/AccessFrameTitle/AccessFrameTitle.jtr
    com/sun/javadoc/AccessSkipNav/AccessSkipNav.jtr
    com/sun/javadoc/AccessFrameTitle/AccessFrameTitle.jtr

I can not find that it has occurred in any other test.

I don't see this type of error for javac.us.oracle.com nor AlanB's on ipwaa69.uk.oracle.com, however there are differences.
For mach 5 we do test runs with -conc:10 (used to use 16, but it didn't speed things up) on a linux machine and we run jtreg with multiple test repositories including langtools/test.
I see javac.us tests run with default setting for -agentvm and Alan Bateman runs with -conc:12 (but runs no langtools tests) and both run 1 workspace(langtools and jdk respectively).

Seems to me the ServerSocket accept() call is hitting that hardcoded 60sec timeout trying to create an agent to build JavadocTester.
While I haven't reproduced this from command line, this occurs fairly regularly running tier1 tests for Mach 5 linux builds.