On 10/15/2014 02:10 AM, David Holmes wrote:
On 14/10/2014 8:46 PM, Jaroslav Bachorik wrote:
Please, review the following test change
Issue : https://bugs.openjdk.java.net/browse/JDK-8056143
Webrev: http://cr.openjdk.java.net/~jbachorik/8056143/webrev.00
The method jdk.testlibrary.ProcessTools.getOutput(process) waits for the
given process to finish (process.waitFor()) before grabbing its outputs.
However, the code does not handle the process.waitFor() being
interrupted correctly - it just goes ahead and tries to obtain the exit
code which will fail and leave the tested process running.
The correct way is to forcibly destroy the process when
process.waitFor() is interrupted or throws ExecutionException to make
sure the process has actually exited before checking its exit code.
Why is this correct? What gives the thread calling getOutput the right
to terminate the target process just because that thread was interrupted
while waiting? If the interrupting thread intended the interrupt to mean
"forcibly terminate the process and interrupt all threads waiting on it"
then that thread should be doing the termination _not_ the one that was
interrupted!
Process.waitFor() gets interrupted by a thread unknown to the actual
test case - probably the JTreg timeout thread. The interrupting thread
doesn't know that it is supposed to destroy a process. Once JTreg can
take care of cleaning up process tree upon exit this code wouldn't be
needed.
I was contemplating adding the check for "null" returned from
ProcessTools.getOutput() and destroying the process inside the caller
code - but this would have the same results as doing it in
ProcessTools.getOutput() with the drawback of duplicating the same check
everywhere ProcessTools.getOutput() would be used.
A silent postcondition of ProcessTools.getOuptut() is that the target
process has finished - and it holds for all the code paths except the
InterruptedException handler.
-JB-
David
Thanks,
-JB-
