RFR(S): 8068579: Running with -XX:-UseParallelGC does not turn ParalleGC off

Per Liden per.liden at oracle.com
Tue Mar 22 09:24:43 UTC 2016


Thanks Bengt!

Per

On 2016-03-22 09:57, Bengt Rutisson wrote:
>
> Hi Per,
>
> Thanks for splitting this up. Looks good!
>
> Bengt
>
> On 2016-03-21 14:03, Per Liden wrote:
>> Hi Bengt,
>>
>> On 2016-03-21 10:56, Bengt Rutisson wrote:
>>>
>>> Hi Per,
>>>
>>> On 2016-03-17 14:36, Per Liden wrote:
>>>> Hi,
>>>>
>>>> On 2016-03-16 09:12, Per Liden wrote:
>>>>> Hi Dima,
>>>>>
>>>>> On 2016-03-15 17:38, Dmitry Fazunenko wrote:
>>>>>> Hi Per,
>>>>>>
>>>>>> A couple of comments:
>>>>>> 1) globals_extension.hpp.frames.html
>>>>>> requires copyright update
>>>>>> 2) such fix should go with a regression test, it could be done
>>>>>> separately.
>>>>>
>>>>> Good point. I was about to add a test for this just now and realized
>>>>> that the new semantics is not kept for minimal VMs (i.e. when
>>>>> INCLUDE_ALL_GCS==0). I'll rework the patch a bit to have the same
>>>>> semantics also on minimal VMs. New webrev coming.
>>>>
>>>> Here's an updated webrev. The new semantics is now available on all
>>>> VMs (including minimal). I also added a new test for this.
>>>>
>>>> This change also removes UNSUPPORTED_GC_OPTION() and instead reuses
>>>> the existing UNSUPPORTED_OPTION(), which I tweaked slightly to make
>>>> the output more consistent across the code base. This in turn meant
>>>> that I needed to adjust some other tests.
>>>>
>>>> http://cr.openjdk.java.net/~pliden/8068579/webrev.1/
>>>
>>> I think this looks good but I think I would prefer to split the changes
>>> up into two separate changes. One for the general UNSUPPORTED_OPTION()
>>> support (that affects the compiler tests etc) and one for the GC default
>>> selection.
>>
>> Thanks for reviewing. Yes, splitting it sounds like a good idea.
>> Here's an updated webrev with only the bug fix.
>>
>> http://cr.openjdk.java.net/~pliden/8068579/webrev.2/
>>
>> I'll file a separate CR for merging the two UNSUPPORTED_XXX macros.
>>
>> thanks,
>> Per
>>
>>>
>>> Overall a very nice cleanup. Thanks for doing this!
>>>
>>> Bengt
>>>
>>>>
>>>> Testing: jprt, manual
>>>>
>>>> thanks,
>>>> Per
>>>>
>>>>>
>>>>> thanks,
>>>>> Per
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Dima
>>>>>>
>>>>>>
>>>>>> On 15.03.2016 16:48, Per Liden wrote:
>>>>>>> Summary: Explicitly disabling the default collector, without
>>>>>>> specifying another collector, will silently re-enable the default
>>>>>>> collector. This is a bit counter intuitive. A better approach
>>>>>>> would be
>>>>>>> for the VM to complain about the situation.
>>>>>>>
>>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8068579
>>>>>>> Webrev: http://cr.openjdk.java.net/~pliden/8068579/webrev.0/
>>>>>>> Testing: manual, jprt
>>>>>>>
>>>>>>> Example (assuming it's a platform/configuration with G1 as default):
>>>>>>>
>>>>>>> $ java -XX:-UseG1GC ...
>>>>>>>
>>>>>>> Today, the above command will happily start a VM with G1 enabled.
>>>>>>>
>>>>>>> With this patch the VM will instead complain, like this:
>>>>>>>
>>>>>>> $ java -XX:-UseG1GC ...
>>>>>>> Error occurred during initialization of VM
>>>>>>> Garbage collector not selected (default collector explicitly
>>>>>>> disabled)
>>>>>>>
>>>>>>> And of course, we're good with disabling the default collector as
>>>>>>> long
>>>>>>> as you specify some other collector, e.g.:
>>>>>>>
>>>>>>> $ java -XX:-UseG1GC -XX:+UseParallelGC ...
>>>>>>>
>>>>>>> cheers,
>>>>>>> Per
>>>>>>
>>>
>


More information about the hotspot-gc-dev mailing list