RFR 8074041: 8074041: sun/management/jmxremote/startstop/JMXStartStopTest.java fails with InvocationTargetException

[Jaroslav Bachorik]

Please, review the following change

Issue : https://bugs.openjdk.java.net/browse/JDK-8074041
Webrev: http://cr.openjdk.java.net/~jbachorik/8074041/webrev.00

This test fails very intermittently still and the failure is very hard 
to reproduce. Based on the symptoms the probable cause seems to be the 
asynchronous processing of a launched process stdout and stderr.

The test is using ProcessTools.startProcess(...) to start the target 
process and process its output (stdout/stderr) to mark the occurrence of 
the expected test. When the target process has finished the test will 
check the mark to assert the correctness. However, it may happen that 
the assertion happens in the time interval between the target process 
finishing (process.waitFor() returns) and the asynchronous stderr/stdout 
processors had the chance to dispatch the target process output to the 
processor checking for the occurrence of the expected test.

The proposed fix is to wrap the Process instance into a wrapper 
enhancing the waitFor() method with the wait for the stdout/stderr 
processor being finished before proceeding. I ran the test in a tight 
loop for 1000 times after applying this patch without any failure.


Thanks,

-JB-