RFR(S): 8228960: [TESTBUG] containers/docker/TestJcmdWithSideCar.java: jcmd reports main class as 'Unknown'

mikhailo.seledtsov at oracle.com mikhailo.seledtsov at oracle.com
Tue Aug 13 00:22:43 UTC 2019

Unfortunately, this approach does not seem to work on many of our test 
cluster machines. The creation of a "signal" file results in 

The possible reason is the selinux configuration, or some other 
permission related stuff. The container tries to create a new file on a 
mounted volume on a host system, but host system denies it. I will look 
a bit deeper into this, but I think this type of issue can be 
encountered on any automated test system. Hence, we may have to abandon 
this approach.



On 8/12/19 3:59 PM, mikhailo.seledtsov at oracle.com wrote:
> Here is an updated webrev: 
> http://cr.openjdk.java.net/~mseledtsov/8228960.01/
> I am using a simple file-based mechanism to communicate between the 
> processes. The "EventGeneratorLoop" process creates a specific 
> "signal" file on a shared mounted volume, while the main test process 
> waits  for the file to exist before running the test cases.
> Passes on Linux-x64 Docker-enabled host. Testing in the test cluster 
> is in progress.
> Thank you,
> Misha
> On 8/7/19 5:11 PM, David Holmes wrote:
>> On 8/08/2019 9:04 am, Mikhailo Seledtsov wrote:
>>> Hi Severin, Bob,
>>>    Thank you for reviewing the code.
>>> On 8/7/19, 11:38 AM, Bob Vandette wrote:
>>>> Can’t you come up with a better way of synchronizing the test by 
>>>> possibly writing a
>>>> file and waiting for it to exist with a timeout?
>>> I will try out this approach.
>> This seems like a fundamental problem with jcmd - so cc'ing 
>> serviceability-dev.
>> But I'm pretty sure they recently addressed a similar issue with the 
>> premature sending of the attach signal?
>> David
>> -----
>>> Thanks,
>>> Misha
>>>> Isn’t there a shared volume between the two
>>>> processes?
>>>> We’ve been fighting test reliability for a while now.  I can only 
>>>> hope we’re getting
>>>> to the end.
>>>> Bob.
>>>>> On Aug 7, 2019, at 2:18 PM, Severin Gehwolf<sgehwolf at redhat.com>>>>> wrote:
>>>>> Hi Misha,
>>>>> On Tue, 2019-08-06 at 20:17 -0700, mikhailo.seledtsov at oracle.com 
>>>>> wrote:
>>>>>> Please review this change that fixes a container test 
>>>>>> TestJcmdWithSideCar.
>>>>>> My investigation indicated that a root cause for this failure is:
>>>>>> JCMD -l shows 'Unknown' for class name because the main class has 
>>>>>> not
>>>>>> been loaded yet.
>>>>>> The target test JVM has started, it is initializing, but has not 
>>>>>> loaded
>>>>>> the main test class.
>>>>> That's what I've found too.
>>>>>> The proposed solution is to try 'jcmd -l' several times, with a 
>>>>>> short
>>>>>> sleep in between.
>>>>> Thread.sleep() isn't great, but I'm not sure there is an alternative.
>>>>>> Also I have commented out the testCase02() due to another bug:
>>>>>> "JDK-8228850: jhsdb jinfo fails with ClassCastException:
>>>>>> s.j.h.oops.TypeArray cannot be cast to s.j.h.oops.Instance",
>>>>>> which is not a test bug. IMO, it is better to run the test and 
>>>>>> skip a
>>>>>> sub-case than to skip the entire test.
>>>>>>      JBS: https://bugs.openjdk.java.net/browse/JDK-8228960
>>>>>>      Webrev: http://cr.openjdk.java.net/~mseledtsov/8228960.00/
>>>>> Looks OK to me.
>>>>> Thanks,
>>>>> Severin

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