From [~dcubed] (edited)

Looks like JTREG has an instance of the ServerSocket bug.

com/sun/javatest/regtest/exec/Agent.java:

private Agent(File dir, JDK jdk, List<String> vmOpts, Map<String, String> envVars,
File policyFile) throws Fault {
<snip>
ServerSocket ss = new ServerSocket(/port:/ 0, /backlog:/ 1);
cmd.add(AgentServer.PORT);
cmd.add(String.valueOf(ss.getLocalPort()));

show("Started " + cmd);

ProcessBuilder pb = new ProcessBuilder(cmd);
pb.directory(dir);
Map<String, String> env = pb.environment();
env.clear();
env.putAll(envVars);
process = pb.start();
copyStream("stdout", process.getInputStream(), System.out);
copyStream("stderr", process.getErrorStream(), System.err);

try {
final int ACCEPT_TIMEOUT = 60*1000; // 1 minute, for server to start and "phone home"
ss.setSoTimeout(ACCEPT_TIMEOUT);
Socket s = ss.accept();}}

The ServerSocket constructor above passes port==0 so it uses an
anonymous port. On platforms where SO_REUSEADDR is enabled
by default, that anonymous port can be stolen by another process
that is also creating a ServerSocket with an anonymous port. The
"interloper" process steals the "connect" that JTREG is waiting for
in the ss.accept() call which results in the failure mode that we're
seeing.