RFR(S) : 8225554 : add JFR event for uncommon trap

[Igor Ignatyev]

ping?

> On Jun 19, 2019, at 5:20 PM, Igor Ignatyev <igor.ignatyev at oracle.com> wrote:
> 
> Hi Markus,
> 
> I definitely support the idea of making the event as helpful for end-users as possible; and having information about the uncommon trap "location" (method, line-number, bci) seems to be very useful. I don't think that 'instruction' field is helpful though b/c w/o seeing the rest of method code it can't be really used to understand what/why happened. what do you think?
> 
> regarding the name, although I don't think this even can be used by people w/o understanding some level of hotspot internals, they at least need to understand what a bit cryptic reasons and actions mean, "Deoptimization" sounds good to me.
> 
> please let me know how you can proceed further here, I can update my patch to rename even and include location info, or I can just withdraw my patch in favor of yours (that's if you plan to finish work on it in near future and it won't be left for other few years :) ) 
> 
> Thanks,
> -- Igor
> 
>> On Jun 18, 2019, at 2:44 AM, Markus Gronlund <markus.gronlund at oracle.com> wrote:
>> 
>> Hi Igor,
>> 
>> Thank you for looking into providing this support.
>> 
>> This work partly overlaps with something I have been working on under the following enhancement:
>> 
>> Enh: https://bugs.openjdk.java.net/browse/JDK-8216041
>> 
>> I have had a patch somewhat semi-ready for some years now, please see:
>> http://cr.openjdk.java.net/~mgronlun/8216041/
>> 
>> Here is what the information set could look visually by default (no structured rendering) in JDK Mission Control:
>> http://cr.openjdk.java.net/~mgronlun/8216041/DeoptimizationEvent.jpg
>> 
>> Maybe we should merge our work for this effort (I am interested in your test case)?
>> 
>> I think we need to take a larger view on this, especially to see if this information could also be made understandable and maybe even useful to the end-user / developer.
>> 
>> This is the reason I choose to use the "deoptimization" concept instead of the more internal UncomonTrap.
>> 
>> Let's see if we together can craft a useful event here.
>> 
>> Thanks
>> Markus
>> 
>> -----Original Message-----
>> From: Igor Ignatyev 
>> Sent: den 11 juni 2019 20:49
>> To: hotspot-jfr-dev at openjdk.java.net; hotspot compiler <hotspot-compiler-dev at openjdk.java.net>
>> Subject: RFR(S) : 8225554 : add JFR event for uncommon trap
>> 
>> http://cr.openjdk.java.net/~iignatyev//8225554/webrev.00/index.html
>>> 187 lines changed: 184 ins; 0 del; 3 mod;
>> 
>> Hi all,
>> 
>> could you please review this small patch which adds jfr event for uncommon trap?
>> 
>> webrev: http://cr.openjdk.java.net/~iignatyev//8225554/webrev.00/index.html
>> JBS: https://bugs.openjdk.java.net/browse/JDK-8225554
>> testing:
>> - tier1 (which includes a newly added test)
>> - modified version of compiler/intrinsics/klass/CastNullCheckDroppingsTest.java (see JDK-8129092[1])
>> 
>> [1] https://bugs.openjdk.java.net/browse/JDK-8129092
>> 
>> Thanks,
>> -- Igor
>