RFR 9: 8143876 : test/java/lang/ProcessHandle/TreeTest.java failed intermittently with assertion error

[Roger Riggs]

Hi Joe,

I do not know of any specific skew issues at the resolutions used. For 
example,
Linux records the start time in ticks  (1/60th to 100th of a second), 
not the full resolution
of the time of day clock. Typically, the child start time is at least a 
bit later
than the parent. If the maximum possible skew was known or estimated, 
the comparison
could take that into account.  For example, I would expect the skew 
across processors
to be less than 1sec (or more likely 10ms) or there would be bigger 
issues among native processes.

Thanks, Roger


On 12/1/15 8:54 PM, Joseph D. Darcy wrote:
> Hi Roger,
>
> Looks fine.
>
> Do you know if there are clock skew issues to be concerned with if the 
> parent and child are spawned on different CPUs?
>
> Thanks,
>
> -Joe
>
> On 12/1/2015 5:49 PM, Roger Riggs wrote:
>> Please review this change in ProcessHandle to validate parent pids 
>> provided by the OS.
>> Children of a process have start times that are the same or later 
>> than the parent.
>> The implementation of descendants(), and children(), and getParent()
>> are updated to validate the parent pid.
>>
>> The problem is most pronounced on Windows; the parent pid reported for a
>> process may be stale if the parent exited.  The validation is applied in
>> platform neutral code and used on all platforms.  Platform specific code
>> is used on Windows for getParent(); the Linux platforms do the right 
>> thing.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~rriggs/webrev-validate-ppid-8143879/
>>
>> Issue:
>>    https://bugs.openjdk.java.net/browse/JDK-8143876
>>
>> Thanks, Roger
>>
>