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List:       openjdk-serviceability-dev
Subject:    Re: JVMTI not receiving field access events with fast_getfield
From:       "serguei.spitsyn () oracle ! com" <serguei ! spitsyn () oracle ! com>
Date:       2017-12-20 20:48:25
Message-ID: dbcaa8b6-8446-33d7-72a2-30a52f47a625 () oracle ! com
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Hi Amir,

As a work around, could you try to enable the 
can_generate_breakpoint_events capability?
This capability should disable the fast get/putfiled bytecodes generation.
Adding this line to the MyAgent.cpp should do it:
      capa.can_generate_breakpoint_events = 1;

Thanks,
Serguei


On 12/20/17 05:40, Amir Rapson wrote:
> Hi,
>
> If you could please remove my phone number from the comments of the bug.
>
> Thanks,
> Amir
>
> -----Original Message-----
> From: Amir Rapson [mailto:amir@vfunction.com]
> Sent: Tuesday, December 12, 2017 3:24 PM
> To: 'daniel.daugherty@oracle.com' <daniel.daugherty@oracle.com>; 'Vladimir
> Ivanov' <vladimir.x.ivanov@oracle.com>;
> 'serviceability-dev@openjdk.java.net' <serviceability-dev@openjdk.java.net>
> Cc: 'Coleen.Phillimore@oracle.com' <Coleen.Phillimore@oracle.com>
> Subject: RE: JVMTI not receiving field access events with fast_getfield
>
> Thank you Dan. Much appreciated.
>
> Again, let me know if I can assist with anything.
>
> Best,
> Amir
>
> -----Original Message-----
> From: Daniel D. Daugherty [mailto:daniel.daugherty@oracle.com]
> Sent: Tuesday, December 12, 2017 3:13 PM
> To: Amir Rapson <amir@vfunction.com>; Vladimir Ivanov
> <vladimir.x.ivanov@oracle.com>; serviceability-dev@openjdk.java.net
> Cc: Coleen.Phillimore@oracle.com
> Subject: Re: JVMTI not receiving field access events with fast_getfield
>
> Amir,
>
> Your https://bugs.openjdk.java.net/browse/JI-9051849 bug has been moved to
> https://bugs.openjdk.java.net/browse/JDK-8193369.
>
> Someone on the Serviceability team should pick up this thread from here, but
> we're right at the end game for JDK10 so it might take some time...
>
> Dan
>
>
> On 12/12/17 8:03 AM, Amir Rapson wrote:
>> Hi,
>>
>> I know the code has some relevant code, but it doesn't seem to work.
>> You will see some differences: the CALL_VM to the post function has
>> only 2 arguments and not 3, I'm not sure it matters.
>>
>> The platform is x86_64, Java version is 1.8.0-152. I can try other
>> versions if you wish.
>>
>> Please find the attached MyAgent.cpp MyAgent.h and
>> com_vfunction_Main.h to compile the agent.
>> Please also find the attached com.vfunction.zip that holds the simple
>> java util to reproduce the problem.
>>
>> You'll see the problem on ArrayList.add(item) where you'll get events
>> only on codes #16 and #22 and not on #2 and #11 (see attached
>> bytecode.txt of said function).
>>
>> Please let me know once you managed to reproduce it. I can also send
>> you a patch file to disable the fast_getfield (and fast putfield) to
>> show that the problem disappears.
>>
>> I'm currently looking at the actual assembly of the add function, both
>> with the modified hotspot and without and will try to assist will
>> offering a fix for this issue.
>>
>> One last thing. I saw a very old issue (resolved by Daniel Daugherty)
>> stating that fast_getfield was not completely addressed with the
>> resolution on this issue. The bug ID is
>> https://bugs.openjdk.java.net/browse/JDK-4300409
>>
>> I'll be happy to assist further.
>>
>> Best regards,
>> Amir
>>
>>
>> -----Original Message-----
>> From: Vladimir Ivanov [mailto:vladimir.x.ivanov@oracle.com]
>> Sent: Tuesday, December 12, 2017 2:46 PM
>> To: Amir Rapson <amir@vfunction.com>
>> Cc: Coleen.Phillimore@oracle.com; daniel.daugherty@oracle.com
>> Subject: Re: JVMTI not receiving field access events with
>> fast_getfield
>>
>> Thanks for the report, Amir!
>>
>> Unfortunately, I can't access the bug you filed.
>>
>> Can you, please, share the test case and instructions how to reproduce
>> the problem?
>>
>> Also, what Java version & platform do you observe the bug on?
>>
>> I briefly looked into template interpreter code on x86 and it does
>> have relevant code to post JVMTI events in fast accessors.
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> On 12/12/17 11:12 AM, Amir Rapson wrote:
>>> Hi Daniel, Coleen and Vladimir,
>>>
>>> I tracked your email addresses from some mailing lists and hopefully
>>> one of you is a relevant person for my problem.
>>>
>>> I also filed a bug request (ID 9051849) but since I don't have an
>>> option to add information I decided to email you.
>>>
>>> The problem I'm seeing is that JMTI does not receive field access
>>> events (and probably field modification events) when /fast_getfield/
>>> is used instead of /get_field/.
>>>
>>> I verified this by disabling all the
>>> /patch_bytecode(Bytecodes::_fast_?getfield, bc, rbx)/ in
>>> /TemplateTable::getfield_or_static()/ and made sure that JVMTI
>>> receives all the correct events.
>>>
>>> I have the agent code and a short java program that can reproduce the
>>> problem and would be happy to assist in fixing and or debugging this
>>> issue.
>>>
>>> I would appreciate any feedback.
>>>
>>> Best regards,
>>>
>>> Amir
>>>
>>> ​​​​​Amir Rapson | Founder & VP Eng @ *vFunction* | 7 HaPelech St.
>>> Tel-Aviv | +972-522650968
>>>

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