RFR(XS): 8166045: jdk/internal/misc/Unsafe tests fail due to timeout

[Mikael Vidstedt]

Thanks for the reviews!

Cheers,
Mikael

> On Sep 26, 2016, at 4:11 PM, Christian Tornqvist <christian.tornqvist at oracle.com> wrote:
> 
> Hi Mikael,
> 
> This looks good, thanks for fixing this.
> 
> Thanks,
> Christian
> 
> On Sep 26, 2016, at 5:53 PM, Mikael Vidstedt <mikael.vidstedt at oracle.com <mailto:mikael.vidstedt at oracle.com>> wrote:
> 
>> 
>> Please review the following change:
>> 
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8166045 <https://bugs.openjdk.java.net/browse/JDK-8166045> 
>> <https://bugs.openjdk.java.net/browse/JDK-8166045 <https://bugs.openjdk.java.net/browse/JDK-8166045>>
>> Webrev: 
>> http://cr.openjdk.java.net/~mikael/webrevs/8166045/webrev.01/jdk/webrev/ <http://cr.openjdk.java.net/~mikael/webrevs/8166045/webrev.01/jdk/webrev/> 
>> <http://cr.openjdk.java.net/~mikael/webrevs/8166045/webrev.01/jdk/webrev/ <http://cr.openjdk.java.net/~mikael/webrevs/8166045/webrev.01/jdk/webrev/>>
>> 
>> Summary:
>> 
>> Among the tests I introduced for Unsafe.copyMemory and Unsafe.copySwapMemory 
>> a few months ago are a couple of tests which rely on being able to allocate 
>> and operate on a large (~2GB) block of native memory. However, on some 
>> smallish machines the actual allocation succeeds, but the machine then goes 
>> on to swap (as in, page to/from disk) like crazy, making the test time out.
>> 
>> In an attempt to work around this I’m using @requires in combination with 
>> the value of os.maxMemory. I could make the whole test(s) conditional on the 
>> memory size, but the vast majority of the test(s) actually operate on a very 
>> small block of memory (tens of bytes), so disabling the whole test seems 
>> unfortunate. Instead I decided to split up the test(s) in two - one set 
>> which tests the default/small size, and one set which tests the large size 
>> iff there is enough memory on the machine.
>> 
>> I have tested manually that the @requires check has the right effect - the 
>> tests are skipped if there’s not enough memory on the machine - and that the 
>> tests still pass as expected.
>> 
>> I also took the liberty of removing a superfluous import.
>> 
>> Cheers,
>> Mikael
>>