RFR 9: 8133552 : java/lang/ProcessHandle/InfoTest.java fails intermittently - incorrect user

[Volker Simonis]

On Wed, Sep 9, 2015 at 11:49 PM, Roger Riggs <Roger.Riggs at oracle.com> wrote:
> Hi,
>
> Please review this update to extract the uid on from the owner of the
> /proc/<pid> file.
> It should be more reliable than using the owner of the /proc/<pid>/cmdline
> file.
>
> Webrev:
>     http://cr.openjdk.java.net/~rriggs/webrev-info-8133552/
>

Hi Roger,

the change looks good. I've only found one little problem:

In:

strncat(fn, "/cmdline", sizeof fn);

'fn' is not empty any more, so I think it should read:

strncat(fn, "/cmdline", sizeof fn - strnlen(fn, sizeof fn) - 1);

Also, increasing the timeout to 30 sec is reasonable.

Thank you and best regards,
Volker

> Thanks, Roger
>
>
>
> On 9/9/2015 12:56 PM, Roger Riggs wrote:
>>
>> Hi Volker,
>>
>> Thanks for the review and diagnosis.
>>
>> Can opening /proc/pid be used as a fallback if the st_uid is zero or
>> is it worth the overhead of stat'ing /proc/pid always?
>>
>> Thanks, Roger
>>
>>
>> On 9/9/2015 11:46 AM, Volker Simonis wrote:
>>>
>>> Hi Roger,
>>>
>>> I think your change looks good and it surely improves the test
>>> stability but I don't think it solves the problem in all cases.
>>>
>>> I think this problem is caused by a <defunct> (i.e. "zombie") process
>>> (the spawned process lived too short and was already a zombie when the
>>> info object was created). If you look at the proc-file system entry of
>>> a <defunct> process you can see that its 'cmdline' file has zero size
>>> and the file is owned by root. This is exactly what is reported by the
>>> corresponding info object in the bug report (user=root and no cmd
>>> field).
>>>
>>> We may need to improve the way how we get the uid of a pid on Linux.
>>> The current way of querying the owner of /proc/<pid>/cmdline seems to
>>> be unreliable. We may instead take the owner of /proc/<pid> which
>>> seems to be still the initial user of the process.
>>>
>>> Regards,
>>> Volker
>>>
>>>
>>> On Tue, Sep 8, 2015 at 11:35 PM, Roger Riggs <Roger.Riggs at oracle.com>
>>> wrote:
>>>>
>>>> With link to webrev corrected:
>>>>
>>>> On 9/8/2015 5:08 PM, Roger Riggs wrote:
>>>>>
>>>>> Please review an intermittent test bug fix.
>>>>> The test setup time is very short and the user may be returned as 0
>>>>> which
>>>>> is reported as root.
>>>>> The correction lengthens the time allowed for the process to start.
>>>>>
>>>>> The test is removed from the ProblemList.
>>>>>
>>>>> Webrev:
>>>>>     http://cr.openjdk.java.net/~rriggs//webrev-info-8133552
>>>>>
>>>>> Bug:
>>>>>    https://bugs.openjdk.java.net/browse/JDK-8133552
>>>>>
>>>>> Thanks, Roger
>>>>>
>>
>