Typical log will look like:

----------System.out:(8/381)----------
--Compiling first version of /cygdrive/c/development/repro/jdi/jtreg/work-c-84/classes/com/sun/jdi/aa6168/shtest.java with options: -g
compiling shtest.java

--Compiling second version of /cygdrive/c/development/repro/jdi/jtreg/work-c-84/classes/com/sun/jdi/aa6168/shtest.java with -g

--Starting jdb, address=kkkk.6168
--Starting debuggee
Listening at address: kkkk.6168
----------System.err:(103/5578)*----------

Looks like we fail to find the jdb process pid in ShellScaffold.sh

$findPidCmd | $grep '^I* *'"$1 " > $devnull 2>&1

Running ps immediately after to verify shows that the process is running.