[11] RFR(S): 8207067: [test] prevent timeouts in serviceability/tmtools/jstat/{GcTest02, GcCauseTest02}.java

[David Holmes]

On 13/07/2018 5:33 PM, Volker Simonis wrote:
> On Thu, Jul 12, 2018 at 11:55 PM, David Holmes <david.holmes at oracle.com> wrote:
>> On 13/07/2018 12:51 AM, Lindenmaier, Goetz wrote:
>>>
>>> Hi Volker,
>>>
>>> I had a look at your change.
>>> Your intent is plausible.
>>>
>>> Won’t it help to just set -XX:+IgnoreUnrecognizedVMOptions?
>>
>>
>> Yes! Great suggestion.
>>
> 
> I wouldn't have believed that it works, because VerifiyDependencies is
> actually not "unknown" but "constant" in non-debug builds. But it
> actually really does!

I was surprised too. :)

> This of course considerably simplifies the change. I've also shortened
> the comment as suggested by David. Please find the updated version
> here:
> 
> http://cr.openjdk.java.net/~simonis/webrevs/2018/8207067.v1/

The comment placement seems odd. You could just add an extra line to the 
@comment part, or just move to be a class level comment rather than 
inside main.

No need to see any update regardless.

Thanks,
David

> OK to push now?
> 
> Thank you and best regards,
> Volker
> 
>>> Alternatively, you could specify two test setups, one with @requires
>>> vm.debug, the
>>> other with !vm.debug.
>>
>>
>> I thought about that one too but the amount of duplicated @xxx stuff looked
>> pretty ugly.
>>
>> Cheers,
>> David
>>
>>
>>> If non of these are possible, your change looks good.
>>>
>>> Best regards,
>>>     Goetz.
>>>
>>>> -----Original Message-----
>>>> From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-
>>>> bounces at openjdk.java.net] On Behalf Of David Holmes
>>>> Sent: Donnerstag, 12. Juli 2018 01:27
>>>> To: Volker Simonis <volker.simonis at gmail.com>; hotspot-runtime-
>>>> dev at openjdk.java.net runtime <hotspot-runtime-dev at openjdk.java.net>
>>>> Subject: Re: [11] RFR(S): 8207067: [test] prevent timeouts in
>>>> serviceability/tmtools/jstat/{GcTest02, GcCauseTest02}.java
>>>>
>>>> Hi Volker,
>>>>
>>>> On 12/07/2018 3:30 AM, Volker Simonis wrote:
>>>>>
>>>>> Hi,
>>>>> can I please have a review for the following test fix which prevents
>>>>> eventual test timeouts:
>>>>>
>>>>> https://bugs.openjdk.java.net/browse/JDK-8207067
>>>>> http://cr.openjdk.java.net/~simonis/webrevs/2018/8207067/
>>>>>
>>>>> The two tests
>>>>
>>>> hotspot/jtreg/serviceability/tmtools/jstat/{GcTest02,GcCauseTest02}.java
>>>>>
>>>>> produce more than 90_000 classes until they eat up ~70% of the 128M
>>>>> meta space they run with. The loading of each of these classes
>>>>> triggers a full dependency check for ALL nmethods in debug/fastdebug
>>>>> builds because 'VerifyDependencies' is 'true' there. This slows down
>>>>> the tests from about 3 sec. in the opt build to about 88 sec. in the
>>>>> fastdebug build on x86_64 and from about 4 sec. to about 560 sec. on
>>>>> ppc64.
>>>>>
>>>>> Because the tests are not about dependency checking, it makes sense to
>>>>> switch of 'VerifyDependencies' if they are run inside a
>>>>> debug/fastdebug VM and decrease the execution time down to about 6
>>>>> sec. on both x86_64 and ppc64.
>>>>
>>>>
>>>> It's very annoying that this can't be fixed the obvious way by just
>>>> specifying -XX:-VerifyDependencies. Maybe jtreg could add a
>>>> debug_only(...)  capability ... :(
>>>>
>>>> It's unclear to me whether it is safe to disable VerifyDependencies
>>>> after the VM has commenced execution. This might lead to
>>>> inconsistencies. Probably need the compiler folk to clarify that.
>>>>
>>>> That aside the comments are far too elaborate and better suited for the
>>>> bug report. The tests could use @bug lines (though it would be nice to
>>>> track down the original bug that added the tests). The comments could
>>>> reduce to a simple:
>>>>
>>>> // This test produces more than 90_000 classes until it eats up ~70% of
>>>> the 128M meta space.
>>>> // With VerifyDependencies enabled in debug builds this slows the test
>>>> down considerably.
>>>> // As it is a develop flag, if we see that it is "constant" then we know
>>>> this is a product build.
>>>>
>>>> Though there is already Platform.isDebugBuild() if you wanted something
>>>> more direct. (Given you need WB to change the flag it doesn't really
>>>> make much difference.)
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>> Thank you and best regards,
>>>>> Volker
>>>>>
>>