RFR: 8142976: TraceClassInitialization has been reimplemented with Unified Logging.

[David Holmes]

Hi Max,

On 25/11/2015 7:27 AM, Max Ockner wrote:
> New webrev @ http://cr.openjdk.java.net/~mockner/ulclassinit02/
> Fixed everything that I said I would fix below.

As a direct conversion of existing logging info this looks fine. The 
overlap with VerboseVerification will have to be dealt with later.

Not sure about the test strategy here in that creating a class that 
fails verification just to check what is logged seem a bit over the top 
and potentially duplicates verifier testing. I wonder if the logging 
test could not in fact run an existing verifier test with logging 
enabled? Which raises the question of whether logging tests like this 
come under logging, or under the subsystem being logged?

In the test EagerInitialization is a develop-only flag, and 
VerboseVerification is diagnostic. It isn't obvious this is being 
handled by the createJavaProcessBuilder calls.

Thanks,
David

>
> On 11/24/2015 3:40 PM, Rachel Protacio wrote:
>> Hi,
>>
>> Looks mostly good, just a few comments:
>>
>> verifier.cpp
>> - at line 118 (the first "Verification for" line), it should just be
>> "print", not "print_cr".
> Thanks. Fixed, though I wonder how much it matters.
>> - between lines 194 and 195, I think you need a ResourceMark for the
>> LogHandle stream.
> The ResourceMark is defined already, it just isn't part of the diffs
> because it was already there.
>> - in the sections starting at lines 179 and 608, I appreciate that you
>> were minimizing the number of lines, but I think it's a bad idea to
>> have duplicates of the logged strings. Do you think you could define
>> the strings outside of the logging and pass it to both functions?
>> Another possible solution would be to make a function to do that with
>> a signature like
>>     void log_multiple(bool enabled1, outputStream* st1, bool enabled2,
>> outputStream* st2, char* msg);
>> that could do this in a more formalized manner. A function like this
>> could be useful for other similar situations as well while we're
>> converting flags one by one. Or what are your thoughts on that?
> Two reasons why I don't think we should do that.
>      (1) We don't want to evaluate format strings unless something is
> being logged. I guess if you can find a way to avoid doing this while
> still making the code look nicer then that is OK. I think it would be
> just as bad to write extra lines of code just to ensure that a short
> string isn't duplicated.
>      (2) We do not guarantee that these two messages will always be the
> same. A conversation I had with Coleen led me to believe we should keep
> the messages separate.
>> - I think the reordered nesting makes sense.
>>
>> ClassInitializationTest.java
>> - nit: can you move the ");"s from the process builder lines onto the
>> lines before them?
> OK.
>>
>> Thanks,
>> Rachel
>>
>> On 11/24/2015 3:09 PM, Max Ockner wrote:
>>> Hello,
>>> Please review my new unified logging code:
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8142976
>>> http://cr.openjdk.java.net/~mockner/ulclassinit01/src/share/vm/classfile/verifier.cpp.cdiff.html
>>>
>>> Summary: -XX:+TraceClassInitialization logging has been reimplemented
>>> using unified logging under the classinit tag.
>>>
>>> In the segment with recursive verification (see verifier.cpp) I
>>> reordered the nested if statement to check was_recursively_verified()
>>> first. I valued clean code over potentially avoiding a function call
>>> to was_recursively_verified.
>>>
>>> What do you think?
>>>
>>> Tested with:
>>> jtreg hotspot tests
>>> new jtreg test for classinit tag
>>> performance testing with refworkload.
>>>
>>> Thanks, Max
>>
>