RFR(S): 8174856: [TESTBUG] Missing DefineClass instances

Dmitry Dmitriev dmitry.dmitriev at oracle.com
Thu Feb 16 10:26:49 UTC 2017

Volker, test change with @requires looks good!

vm.compMode is an extension Jtreg requires name, so it's not listed in 
Jtreg documentation. It seems that the only reliable way is to look into 
hotspot test suite config file hotspot/test/TEST.ROOT. This file mention 
additional properties for hs tests:
requires.extraPropDefns = ../../test/jtreg-ext/requires/VMProps.java 

VMProps.java define following properties:
         map.put("vm.flavor", vmFlavor());
         map.put("vm.compMode", vmCompMode());
         map.put("vm.bits", vmBits());
         map.put("vm.flightRecorder", vmFlightRecorder());
         map.put("vm.simpleArch", vmArch());
         map.put("vm.debug", vmDebug());
         map.put("vm.jvmci", vmJvmci());
         map.put("vm.emulatedClient", vmEmulatedClient());
         map.put("vm.cpu.features", cpuFeatures());
         vmGC(map); // vm.gc.X = true/false

I hope this helps in the future!


On 16.02.2017 13:06, Volker Simonis wrote:
> On Wed, Feb 15, 2017 at 6:46 PM, Dmitry Dmitriev
> <dmitry.dmitriev at oracle.com> wrote:
>> Hello Volker,
>> I think this can be simplified by using isComp() method of Platform class
>> from jdk.test.lib package(test/lib/jdk/test/lib/Platform.java). Also, I
>> think it is possible to specify VM mode in @requires tag(I think it's best
>> solution to exclude test with "-Xcomp" flag), but I need to check that
>> tomorrow.
> Hi Dmitry,
> thanks for you comments. I think you are right and I agree that a
> @requires tag is the simplest and most effective way of excluding
> these test in -Xcomp mode. I use @requires vm.compMode != "Xcomp".
> Please find the new webrev here:
> http://cr.openjdk.java.net/~simonis/webrevs/2017/8174856.v2/
> By the way, is there an up to date list of all the available require
> names? I only found
> http://openjdk.java.net/jtreg/tag-spec.html#requires_names but it
> doesn't contain vm.compMode != "Xcomp" for example.
> Regards,
> Volker
>> Thank you,
>> Dmitry
>> On 15.02.2017 20:32, Volker Simonis wrote:
>>> Hi,
>>> so here's an alternative version which doesn't execute the tests in -Xcomp
>>> mode:
>>> http://cr.openjdk.java.net/~simonis/webrevs/2017/8174856.v1/
>>> Instead of using a wrapper test which seems overly complicated to me
>>> :) I just use MX to query the command line and return if either
>>> '-Xcomp' or '-XX:-UseInterpreter' was specified.
>>> Please choose whichever of the two versions you like.
>>> Regards,
>>> Volker
>>> PS: it would be great if you could run the exact test that failed
>>> before just in case there will be other problems as well. I've just
>>> checked that the test now succeed in both, normal and '-Xcomp' mode.
>>> On Wed, Feb 15, 2017 at 10:17 AM, David Holmes <david.holmes at oracle.com>
>>> wrote:
>>>> Hi Volker,
>>>> On 15/02/2017 5:51 PM, Volker Simonis wrote:
>>>>> On Wed, Feb 15, 2017 at 12:46 AM, David Holmes <david.holmes at oracle.com>
>>>>> wrote:
>>>>>> Hi Volker,
>>>>>> Can we just skip the test in -Xcomp mode?
>>>>> That would be fine for me, but how would I detect that? -Xcomp is not
>>>>> a VM flag, it is specially handled at startup and sets the following
>>>>> actual flags:
>>>>>     case _comp:
>>>>>       UseInterpreter           = false;
>>>>>       BackgroundCompilation    = false;
>>>>>       ClipInlining             = false;
>>>>>       if (TieredCompilation) {
>>>>>         Tier3InvokeNotifyFreqLog = 0;
>>>>>         Tier4InvocationThreshold = 0;
>>>>>       }
>>>>> Do you think it is safe to check for all these flags and skip the test
>>>>> if they are set correspondingly?
>>>> A simpler approach would be to run a wrapper test in driver mode, so no
>>>> VM
>>>> flags are passed through, and then exec the real test in a VM with
>>>> minimal
>>>> flags set.
>>>>> Why do you actually think we should skip the test in -Xcomp mode? Do
>>>>> you think it became too complicated/unstable? The good thing about
>>>>> running it in -Xcomp mode is that it now also checks that we get rid
>>>>> of the instance classes which are referenced by the nmethods.
>>>> Xcomp is a stress mode that can sometimes change the normal way things
>>>> work,
>>>> so we sometimes end up not actually testing what we intended to test when
>>>> run in Xcomp mode.
>>>> In this case I don't know enough about what is happening to evaluate the
>>>> techniques you have used to deal with Xcomp mode. So I can't review this
>>>> as-is.
>>>> Would love to get other opinions on this.
>>>> Thanks,
>>>> David
>>>>> But as I said, I'm open for both solutions. Please let me know what you
>>>>> think.
>>>>> Regards,
>>>>> Volker
>>>>>> David
>>>>>> On 15/02/2017 4:31 AM, Volker Simonis wrote:
>>>>>>> Hi,
>>>>>>> can I please have a reviewer and sponsor for the following fix:
>>>>>>> http://cr.openjdk.java.net/~simonis/webrevs/2017/8174856/
>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8174856
>>>>>>> The runtime/Metaspace/DefineClass.java test introduced with 8173743
>>>>>>> fails if run in '-Xcomp' mode. There are actually two problems we
>>>>>>> observe:
>>>>>>> - for the "defineClass" and "defineClassParallel" cases we observe
>>>>>>> fewer instance classes than expected. This is because in -Xcomp mode
>>>>>>> the functions get compiled and deoptimized, but because we don't
>>>>>>> really use the defined classes, they are already removed before our
>>>>>>> first check. This problem can be easily fixed by inserting the classes
>>>>>>> into a global static list.
>>>>>>> - for the "redefineClass" case, if run in -Xcomp mode, the problem is
>>>>>>> that we get 10 different nmethods for each version of the class
>>>>>>> redefinition, and these nmethods keep the instance classes alive, even
>>>>>>> after their activation has been removed from the stack. The problem
>>>>>>> can be solved by manually deoptimizing the methods and subsequent
>>>>>>> sweeping of the code cache. Notice that this has to be done at least
>>>>>>> three times, because during every sweep process, the nmethods first
>>>>>>> transition from "non-entrant" to "zombie" before they are finally
>>>>>>> cleaned.
>>>>>>> Thank you and best regards,
>>>>>>> Volker

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