RFR 8214572: nsk/jvmti/unit/ForceEarlyReturn/earlyretbase should not suspend the thread when the top frame executes JVMCI code

Wed Dec 5 00:55:55 UTC 2018

On 12/4/18 4:54 PM, David Holmes wrote:
> Hi everyone,
>
> I'd actually argue that the comment not refer just to JVMCI but more 
> generally:
>
> +         // when the top frame belongs to the test rather than to 
> incidental Java code (classloading, JVMCI, etc)

Reasonable.

> Also note typo: then -> than

Nice catch!

Thanks,
Serguei

>
> Cheers,
> David
>
> On 5/12/2018 5:40 am, serguei.spitsyn at oracle.com wrote:
>> Hi Daniil,
>>
>> It looks good in general.
>> Thank you for the update!
>>
>> I have some minor comment though.
>>
>> http://cr.openjdk.java.net/%7Edtitov/8214572/webrev.02/test/hotspot/jtreg/vmTestbase/nsk/share/jvmti/jvmti_tools.h.udiff.html 
>>
>>
>> +/**
>> +* This method suspends the thread while ensuring the top frame 
>> executes the test method
>> +* rather then JVMCI code triggered by invocation counter overflow.
>> +*/
>> +int suspendThreadAtMethod(jvmtiEnv *jvmti, jclass cls, jobject 
>> thread, jmethodID method);
>>
>>
>> The comment above is not precise as it tells nothing about top frame.
>>
>> I like this one from implementation:
>>
>> + // We need to ensure that the thread is suspended at the right place
>> + // when the top frame belongs to the test rather then to JVMCI code.
>>
>>
>> So, the can be rephrased to something like:
>>
>> + // This method makes the thread to be suspended at the right place
>> + // when the top frame belongs to the test rather then to JVMCI code.
>>
>>
>>
>> No need in another webrev if you fix the comment.
>>
>> Thanks,
>> Serguei
>>
>>
>> On 12/4/18 10:24 AM, Daniil Titov wrote:
>>>
>>> Hi Serguei and JC,
>>>
>>> Thank you for reviewing this change. And many thanks to David and 
>>> Dean for answering JVMCI questions.
>>>
>>> Please review a new version of the fix that moves the most of the 
>>> new code in a helper method ( as JC suggested) and corrects error 
>>> messages. I also excluded the changes in 
>>> test/hotspot/jtreg/ProblemList-graal.txt from this webrev.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8214572
>>>
>>> Webrev:http://cr.openjdk.java.net/~dtitov/8214572/webrev.02/ 
>>> <http://cr.openjdk.java.net/%7Edtitov/8214572/webrev.02/>
>>>
>>> Thanks,
>>>
>>> --Daniil
>>>
>>> *From: *"serguei.spitsyn at oracle.com" <serguei.spitsyn at oracle.com>
>>> *Date: *Monday, December 3, 2018 at 4:14 PM
>>> *To: *Daniil Titov <daniil.x.titov at oracle.com>, serviceability-dev 
>>> <serviceability-dev at openjdk.java.net>
>>> *Subject: *Re: RFR 8214572: 
>>> nsk/jvmti/unit/ForceEarlyReturn/earlyretbase should not suspend the 
>>> thread when the top frame executes JVMCI code
>>>
>>> Hi Daniil,
>>>
>>> It looks good in general.
>>>
>>> I have two comments though.
>>>
>>> -vmTestbase/nsk/jvmti/unit/ForceEarlyReturn/earlyretbase/TestDescription.java 
>>> 8195635   generic-all
>>>
>>>   It is not a good idea to remove the test from the ProblemList 
>>> before the 8195635 is fixed.
>>>
>>> 148     if(method == midActiveMethod) {
>>>   149         printf("<<<<<<<< SuspendThread() is successfully 
>>> done\n");
>>> 150     } else {
>>> 151         printf("Warning: method \"activeMethod\" was missed\n");
>>> 152         errCode = STATUS_FAILED;
>>> 153     }
>>>
>>>  I'd suggest to tweak the error message to something like:
>>>    "Failed in the suspThread: was not able to suspend thread with 
>>> the activeMethod() on top\n");
>>>
>>>
>>> Thanks,
>>> Serguei
>>>
>>> *From: *JC Beyler <jcbeyler at google.com>
>>> *Date: *Friday, November 30, 2018 at 7:47 PM
>>> *To: *<daniil.x.titov at oracle.com>
>>> *Cc: *<serviceability-dev at openjdk.java.net>
>>> *Subject: *Re: RFR 8214572: 
>>> nsk/jvmti/unit/ForceEarlyReturn/earlyretbase should not suspend the 
>>> thread when the top frame executes JVMCI code
>>>
>>> Hi Daniil,
>>>
>>> The webrev looks good but I have a few comments and questions (if 
>>> you don't mind :-)):
>>>
>>> Comments:
>>>
>>>   - You say that normally the test will be removed from the problem 
>>> list once the two fixes are done but in this webrev, you've already 
>>> removed it (I can't see the other case so I can't see if it is 
>>> resolved :-))
>>>
>>>   - now that we are in C++ for the tests, could we not declare the 
>>> variables at their first use instead of doing the pedantic top of 
>>> the block C style?
>>>
>>>   - I feel that this sort of "wait until we are not in JVMCI frames" 
>>> might happen a lot, maybe we could move that code into a helper 
>>> method (+ it cleans the method a bit to just concentrate on the 
>>> rest) and then if needed we can make it public to other tests?
>>>
>>> Questions because I'm not familiar with JVMCI consequences so not 
>>> really comments on the webrev but so that I know:
>>>
>>>   - Is it normaly that you can suspend when you are in a JVMCI 
>>> frame? will/is there not a better way that we could detect that we 
>>> are in a JVMCI frame? Is it always safe to suspend a JVMCI frame?
>>>
>>> Thanks!
>>>
>>> Jc
>>>
>>>
>>>
>>>
>>> On 11/30/18 19:08, Daniil Titov wrote:
>>>
>>>     Please review the change for 
>>> nsk/jvmti/unit/ForceEarlyReturn/earlyretbase test. The problem here 
>>> is that before doing an early force return the test doesn't check 
>>> that the test thread is suspended at a right place where the top 
>>> frame executes the test method rather than JVMCI code triggered by 
>>> invocation counter overflow. That results in the early return 
>>> happens for a wrong method and the test fails.
>>>
>>>     The fix changes the test to do resume/suspend in the loop until 
>>> the target method is executed in the top frame or the loop counter 
>>> exceeds the limit.
>>>
>>>     There is another problem with this test that requires changes on 
>>> VM side and is currently covered by JDK-8195635:" [Graal] 
>>> nsk/jvmti/unit/ForceEarlyReturn/earlyretbase crashes with assertion 
>>> "compilation level out of bounds"".  The test will have to be 
>>> removed from test/hotspot/jtreg/ProblemList-graal.txt only after 
>>> both these issues are fixed.
>>>
>>>     Bug:https://bugs.openjdk.java.net/browse/JDK-8214572
>>>
>>> Webrev:http://cr.openjdk.java.net/~dtitov/8214572/webrev.01/ 
>>> <http://cr.openjdk.java.net/%7Edtitov/8214572/webrev.01/>
>>>     Thanks,
>>>
>>>     Daniil
>>>
>>>
>>>
>>