RFR(S): 8240634: event/runtime/TestMetaspaceAllocationFailure.java times out

[mikhailo.seledtsov at oracle.com]

Here is an updated webrev: 
http://cr.openjdk.java.net/~mseledtsov/8240634.01/

On 3/25/20 4:55 PM, mikhailo.seledtsov at oracle.com wrote:
> Erik, Thomas,
>
>   Thank you for reviewing this change. See my comment inline:
>
> On 3/25/20 7:06 AM, Thomas Stüfe wrote:
>> Hi Mikhailo, Erik,
>>
>> You should not need the additional -XX:MaxMetaspaceSize=200M. As a 
>> rule of thumb, in compressed class space, each class takes about 1K 
>> (bit less actually) so 200M give you room for about 200000 - 250000 
>> classes to load before OOM. I'd say that is way too much for this 
>> test. You just want enough to load the base jdk and get the test 
>> running and then you want to hit OOM quickly.
>>
>> I tested the test with CompressedClassSpaceSize=10M (which would give 
>> us about 10000 classes) and that still worked fine, so I think you 
>> could just drastically lower CompressedClassSpaceSize.
> Thank you for detailed explanation. For the second test case (second 
> @run statement), I have set the CompressedClassSpaceSize to 10M. I ran 
> the test many times on Linux, Windows and Mac, and it works well.
>>
>> Also why the Thread.sleep(100) in the loop? Maybe it would make more 
>> sense to make the fill-loop tight or with only minimal sleep time, 
>> and instead have a loop at the outside waiting for the even to arrive?
>
> I have removed the sleep, and it seems to work fine.
>
> Since these both are trivial updates, I will go ahead and integrate 
> the change.
>
>
> I also agree with Erik, if this test keeps being unstable I am 
> inclined to remove it.
>
>
> Thank you,
>
> Misha
>
>>
>> Cheers, Thomas
>>
>> On Wed, Mar 25, 2020 at 1:24 PM Erik Gahlin <erik.gahlin at oracle.com 
>> <mailto:erik.gahlin at oracle.com>> wrote:
>>
>>     Hi Misha,
>>
>>     Looks OK
>>
>>     Relying on OOM and parameters being correct to trigger the event 
>> seem
>>     fragile, but let's try this and if it fails again, let's remove
>>     the test
>>     or come up with another approach.
>>
>>     Thanks
>>     Erik
>>
>>     On 2020-03-18 02:24, mikhailo.seledtsov at oracle.com
>>     <mailto:mikhailo.seledtsov at oracle.com> wrote:
>>     > This test timed out occasionally, about 1/100 runs, on Linux only.
>>     > Please review this change that mitigates occasional test failure
>>     > by limiting the number of iterations attempting to fill up
>>     metaspace,
>>     > and throwing SkippedException when the max number
>>     > of iterations is reached.
>>     >
>>     >     JBS: https://bugs.openjdk.java.net/browse/JDK-8240634
>>     >     Webrev: http://cr.openjdk.java.net/~mseledtsov/8240634.00/
>>     >     Testing:
>>     >         Ran 100 times on Linux, 1 skipped, rest PASS
>>     >
>>     >
>>     > Thank you,
>>     > Misha
>>     >
>>