Question regarding 8248521: TestVerifyIterativeGVN.java is failing with timeout

[Christian Hagedorn]

Hi Goetz

As Fairoz has mentioned, JDK-8246203 changed the algorithm slightly such 
that it needs now more time for the verification (we check more nodes 
than before).

JDK-8246203 originally only happened in JDK-11 with 
-XX:+VerifyIterativeGVN where a stack overflow crash occurred with a 
more or less HelloWorld test (the old algorithm as a recursive one). It 
turned out that with JDK-11 it compiled a specific big method which 
generated quite a lot of nodes in a chain which let it crash. However, 
with JDK-15 (and 16), this method was not compiled anymore as part of a 
HelloWorld test. It probably got changed since JDK-11 or is not called 
anymore when starting up. Therefore, we concluded that it must be an 11 
only issue and just increased the timeout for the test as we have not 
seen timing it out in JDK-15 or 16.

Best regards,
Christian

On 10.07.20 10:06, Lindenmaier, Goetz wrote:
> Hi Fairoz,
> 
> Thanks for the info.
> 
> It's still unclear to me why the algorithm takes longer in 11
> than in 15 ... but no matter.
> 
> Best regards,
>    Goetz.
> 
> From: Fairoz Matte <fairoz.matte at oracle.com>
> Sent: Friday, July 10, 2020 10:01 AM
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>
> Cc: hotspot-compiler-dev at openjdk.java.net
> Subject: RE: Question regarding 8248521: TestVerifyIterativeGVN.java is failing with timeout
> 
> Hi Goetz,
> 
> This issue is only applicable to 11u.
> After the fix of JDK-8246203,  which changed the algorithm for the verification used with VerifyIterativeGVN (takes more time)
> We have adjusted timeout to 1200 from 600.
> 
> Thanks,
> Fairoz
> 
> From: Lindenmaier, Goetz <goetz.lindenmaier at sap.com<mailto:goetz.lindenmaier at sap.com>>
> Sent: Friday, July 10, 2020 12:11 PM
> To: Fairoz Matte <fairoz.matte at oracle.com<mailto:fairoz.matte at oracle.com>>
> Cc: hotspot-compiler-dev at openjdk.java.net<mailto:hotspot-compiler-dev at openjdk.java.net>
> Subject: Question regarding 8248521: TestVerifyIterativeGVN.java is failing with timeout
> 
> Hi Fairoz,
> 
> we also see this test timing out on mac. But only so with
> jdk11u.
> Do you mind sharing how you fixed this? Did you just increase
> the timeout, or did you figure out why this fails on mac in 11u?
> 
> Thanks,
>    Goetz
>