RFR: 8219149: ProcessTools.ProcessBuilder should print timing info for subprocesses

[Kim Barrett]

> On May 29, 2019, at 3:39 PM, Daniel D. Daugherty <daniel.daugherty at oracle.com> wrote:
> 
> On 5/29/19 1:24 PM, Kim Barrett wrote:
>> [I’m not completely sure where this RFR should be sent, but core-libs-dev
>> and hotspot-dev seems likely to get reasonable coverage of those who
>> might care.]
>> 
>> Please review this change to the test library to add some "logging"
>> output to tests that spawn a child process to perform the test and
>> then analyze that child's output.  We are seeing occasional timeouts
>> in such tests whose cause is hard to pin down.  It's not clear whether
>> the excess time is in the child or instead some problem in the testing
>> framework.  The new logging output provides timestamps for (1) the
>> start of output collection from the child, (2) the start of waiting
>> for the child to terminate, and (3) the child's termination.  This
>> should be enough to determine whether the child is taking too long,
>> and hint at where (e.g. termination or not).
>> 
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8219149
>> 
>> Webrev:
>> http://cr.openjdk.java.net/~kbarrett/8219149/open.00/
> 
> test/lib/jdk/test/lib/process/OutputBuffer.java
>     Based on the Java doc, it looks like the timestamp portion
>     will look something like this:  '2011-12-03T10:15:30Z’

The timestamp includes trailing “.microseconds” (at least, it looks like microseconds).

>     I like it. Since I've been chasing some of the timeout bugs
>     in the CI, I look forward to seeing the new output...
> 
> Thumbs up.

Thanks.