RFR: 8209585: [Graal] vmTestbase/nsk/jvmti/scenarios/sampling tests fail with "Too small stack of resumed thread"

[JC Beyler]

Hi Serguei,

Fair enough, at least this removes a bit of the chance of flakiness :-)

Should we at least clean up the comment for methods that are changed?

/**
 * Testcase: check tested threads
 *    - invoke getFrameCount() for each thread
 *    - check if frameCount is not less than minimal stack depth
 *    - invoke getStackTrace() for each thread
 *    - check if stack depth is not less than frameCount
 *    - for suspended thread check if stack depth is equal to frameCount
 *
 * Returns NSK_TRUE if test may continue; or NSK_FALSE for test break.
 */
static int checkThreads(int suspended, const char* kind) {

The "  *    - check if stack depth is not less than frameCount" is no
longer done with this webrev.

Thanks,
Jc


On Sun, Aug 26, 2018 at 9:52 PM serguei.spitsyn at oracle.com <
serguei.spitsyn at oracle.com> wrote:

> Hi Jc,
>
> Initially, I has the same concern.
> But now I think there is no point to take these values on non-suspended
> threads.
> It has to be good enough to compare the values taken on suspended threads
> only.
>
> Thanks,
> Serguei
>
>
> On 8/24/18 16:49, JC Beyler wrote:
>
> Hi Daniil,
>
> Just my two cents about this :)
>
> I was looking at this and wondered if it made sense to fix the test this
> way (I always worry about simplifying a test and losing coverage). I
> understand the bug is that it is possible that between both calls, Graal
> could add some frames and therefore might trip this test:
>
> -        if (frameStackSize < frameCount) {
>
> However, by removing the test altogether and only relying on the suspended
> frames, are we not reducing our coverage of the test (basically never
> really testing the running threads anymore, only the suspended ones?).
>
> Alternatively, when we look at this code and the hypothesis of Graal
> stacks "slipping in between calls", two cases could occur:
>   A) The Graal frames are present in the first call but not the second
>   B) The Graal frames are present in the second call but not the first
>
> In the (B) case, the test would not trip, as frameStackSize would be >=
> frameCount so that is not an issue.
> In the (A) case, we could simply recall the frameCount and assure
> ourselves the frames have disappeared, no?
>
> Something like:
>
>         if (frameStackSize < frameCount) {
>            // This can occur for Graal if graal frames crept in. Call
> getFrameCount again and see if they have disappeared since
>           // frameStackSize seems to say so.
>            ... insert call here and a new check...
>
>             NSK_COMPLAIN5("Too small stack of %s thread #%d (%s):\n"
>                             "#   getStackTrace(): %d\n"
>                             "#   getFrameCount(): %d\n",
>                             kind, i, threadsDesc[i].threadName,
>                             (int)frameStackSize, (int)frameCount);
>             nsk_jvmti_setFailStatus();
>         }
>
> Just my 2 cents because I worry about simplifying a test for Graal but
> losing coverage in the general case,
> Jc
>
>
>
> On Thu, Aug 23, 2018 at 8:29 PM Daniil Titov <daniil.x.titov at oracle.com>
> wrote:
>
>> Please review the change that fixes 4 JVMTI tests when running with Graal.
>>
>> One of the checks these tests perform compares the number of frames in
>> the thread's stack returned by JVMTI GetFrameCount() with the number of
>> frames entries returned by JVMTI GetStackTrace(). The thread to be tested
>> executes arithmetic operations in the loop so the consequent calls of
>> GetFrameCount() or/and  GetStackTrace() should return the stack trace of
>> the same depth.
>>
>> However,  with Graal on, additional "adjustCompilationLevel" frames could
>> appear on the stack trace, e.g.:
>>
>> adjustCompilationLevel:166, HotSpotGraalCompilerFactory
>> (org.graalvm.compiler.hotspot)
>> adjustCompilationLevel:504, HotSpotJVMCIRuntime (jdk.vm.ci.hotspot)
>> testedMethod:56, Test$Runner
>> run:67, Test$Runner
>>
>> that results in the stack depth reported by the first invocation of
>> GetFrameCount() or GetStackTrace() might differ from the stack depth
>> reported by the consequent calls of the same methods.
>>
>> The fix modifies the tests to ensure the check that GetFrameCount () and
>> GetStackTrace() report the same stack depth is performed only if the thread
>> is suspended. For two tests
>> (vmTestbase/nsk/jvmti/scenarios/sampling/SP02/sp02t001/TestDescription.java
>> and
>> vmTestbase/nsk/jvmti/scenarios/sampling/SP06/sp06t001/TestDescription.java)
>> such check for suspended threads already exists so in these tests the
>> problematic check was not modified by just removed.
>>
>> Issue: https://bugs.openjdk.java.net/browse/JDK-8209585
>> Webrev: http://cr.openjdk.java.net/~dtitov/8209585/webrev.01
>>
>> Thanks,
>> Daniil
>>
>>
>>
>
> --
>
> Thanks,
> Jc
>
>
>

-- 

Thanks,
Jc
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