RFR: 8248266: ZGC: TestUncommit.java fails due to "Exception: Uncommitted too fast" again

[Per Liden]

Thanks Erik!

/Per

On 8/18/20 1:33 PM, Erik Österlund wrote:
> Hi Per,
> 
> Looks good.
> 
> Thanks,
> /Erik
> 
> On 2020-08-18 11:39, Per Liden wrote:
>> Hi!
>>
>> Most people are back from vacations now (including myself), so I'm 
>> giving this thread a bump as I'm still looking for reviews on this 
>> change.
>>
>> cheers,
>> Per
>>
>> On 6/26/20 3:28 PM, Per Liden wrote:
>>> Hi,
>>>
>>> The test gc/z/TestUncommit.java sometimes fail because of bad timing, 
>>> caused by what appears to be an heavily loaded machine so the test 
>>> thread doesn't get to execute in a timely manner.
>>>
>>> I've restructured the test a bit, to be less sensitive to this. 
>>> Instead of sleeping and then checking if uncommit has happened, the 
>>> test will now wait until uncommit happens and record the time. When 
>>> checking the time it now uses TIMEOUT_FACTOR to control how strict 
>>> the check should be.
>>>
>>> To keep things simple, I've also broken out the part that tests with 
>>> uncommit disabled into a separate test.
>>>
>>> The change in ZPage/ZPageCache rounds up the last_used/last_committed 
>>> timestamps to the nearest second. Without this we will always be 
>>> rounding the time down, which means we can sometimes uncommit one 
>>> second too early, which is wrong but not a big problem, but this can 
>>> also cause TestUncommit.java to fail with "Uncommitted too fast".
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8248266
>>> Webrev: http://cr.openjdk.java.net/~pliden/8248266/webrev.0
>>>
>>> Testing: Ran TestUncommit 100+ times on all Oracle-platforms.
>>>
>>> /Per
>