RFR 8220684 : Process.waitFor(long, TimeUnit) can return false for a process that exited within the timeout

[David Holmes]

Hi Ivan,

On 15/03/2019 5:49 am, Ivan Gerasimov wrote:
> Hello!
> 
> The default implementation of Process.waitFor(long, TimeUnit) does not 
> check if the process has exited after the last portion of the timeout 
> has expired.

Please clarify. There is always a race between detecting a timeout and 
the process actually terminating. If the process actually terminates 
while you're deciding to report a timeout that seems just  an acceptable 
possibility. No matter what you do the process could terminate just 
after you decided to report the timeout.

David
-----

> JDK has two implementations of Process (for Unix and Windows) and they 
> both override waitFor(), so it's not an issue for them.
> 
> Still, it is better to provide a more accurate default implementation.
> 
> I'm not quite certain the regression test needs to be included in the 
> fix.  The test does demonstrate the issue with the unfixed JDK and 
> passed Okay on all tested platforms in Mach5.  Yet, I suspect the test 
> can still show false negative results, as there are no guaranties that 
> even such simple application as `true` will finish in 100 ms.
> I can tag the test as @ignored with a comment, or simply remove it from 
> the fix.
> 
> BUGURL: https://bugs.openjdk.java.net/browse/JDK-8220684
> WEBREV: http://cr.openjdk.java.net/~igerasim/8220684/00/webrev/
> 
> Thanks in advance for reviewing!
>