RFR (L): JDK-6843347 Boundary values in some public GC options cause crashes

[Jon Masamitsu]

On 5/3/2013 9:22 AM, Thomas Schatzl wrote:
> Hi Jon,
>
>    thanks for your comments.
>
> On Fri, 2013-05-03 at 08:57 -0700, Jon Masamitsu wrote:
>> Why a minimum value of CMSPrecleanThreshold as 100?  A value as low as 1
>> works, right?
> In concurrentMarkSweepGeneration.cpp, line 4591 there is an assert
> checking:
>
>    assert(CMSPrecleanThreshold >= 100,
>           "Unreasonably low CMSPrecleanThreshold");
>
> I.e. these min/max values are sometimes derived from walking through the
> code and trying to satisfy assertions, otherwise using a value that
> while maybe crazy at least does not crash or completely disable
> operation (i.e. running into infinite loops).

Stay with 100.

>
>> Should we make the minimum for HeapSizePerGCThread 1 page and document it
>> that way?  A value of 1 is legal but it's a crazy value and if anyone
>> uses 1, they've made a mistake.
>>
>> +  status = status && verify_min_value(HeapSizePerGCThread, 1, "HeapSizePerGCThread");
>>
>> Rest looks good.
> Fine with me. I will change the code accordingly. I will prepare a new
> webrev; please tell me if you want me to fix the CMSPrecleanThreshold
> too.

Thanks.

Jon
>
> Thanks,
>    Thomas
>
>