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

[mikhailo.seledtsov at oracle.com]

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
>     >
>