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

[Erik Österlund]

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