RFR: 8142366: Add develop_debug and develop_trace levels to Unified Logging

[Marcus Larsson]

Hi,

I don't think this is the right approach for this problem.

These new develop levels are introduced as even finer levels than the 
trace, but have names that somewhat say otherwise.
For example, develop_info is finer than trace, but it isn't unreasonable 
to expect that develop_info actually shares verbosity with the regular 
info level.


I see two ways to look at this:

1) develop is a level, which is so verbose/expensive that it is not 
possible to include it in the product (current implementation).
The following levels are used: error, warning, info, debug, trace and 
develop. There is no concept of levels for the develop only logging (it 
IS the level).
Selecting/distinguishing different logging on develop level is done by 
using tags.

2) There is no concept of a develop level, either the logging is 
included in product or it isn't (compare to using #ifdefs around the 
logging calls).
Development-only logging is orthogonal to the regular log levels, i.e. 
some log_info calls should only be made in non-product builds 
(log_develop_info),
but should still follow the regular log level system (as all other 
logging does) and use the info level.
The following levels are used: error, warning, info, debug, trace, and 
convenience macros are used to strip develop-logging from non-product 
builds.

The downside of this approach is that it becomes harder to distinguish 
what is logged only in non-product builds and what is always logged.
Depending on if the build is non-product or not one can get different 
output for "-Xlog".


The current proposal mixes these two approaches and adds develop 
"levels" that are all finer than trace, which is confusing.

In my opinion, there should be no reason to require multiple levels for 
non-product logging. I would assume all develop level logging to be very 
specific, i.e. have a very specific tagset,
and require no support for selection/separation using log levels. If it 
does, then I would argue for that the logging is missing some 
classifying log tag that could be used instead of a level.
The logging has already been classified as verbose/expensive, why 
classify it further on a level scale?

Thanks,
Marcus


On 2015-11-11 00:13, Coleen Phillimore wrote:
>
> I think this looks good.   I added serviceability-dev to the mailing 
> list.
>
> Coleen
>
> On 11/10/15 2:18 PM, Rachel Protacio wrote:
>> Good point. I have changed Develop to DevelopInfo. I think it's 
>> better to maintain the same levels of levels on the develop side so 
>> that the logging can just shift laterally to non-product, as it were.
>>
>> And yes, they are specified as -Xlog:<tag>=develop_debug
>>
>> Updated webrev: http://cr.openjdk.java.net/~rprotacio/8142366.01/
>> I re-tested with logging jtreg tests and ExecuteInternalVMTests test, 
>> and for anyone who was curious (namely Max who had the good idea for 
>> me to check), the debug levels do correctly "nest" with more verbose 
>> ones printing out the less verbose and product mode logging as well.
>>
>> Thanks,
>> Rachel
>>
>> On 11/9/2015 6:05 PM, Coleen Phillimore wrote:
>>>
>>> Hi Rachel,
>>>
>>> I sort of thought DevelopDebug would replace plain Develop, and 
>>> DevelopTrace would be additional lower level.   Maybe plain Develop 
>>> should be DevelopInfo then?
>>>
>>> Another question - how do you specify these levels?  Is it 
>>> -Xlog:itables=develop_debug ?
>>>
>>> Thanks,
>>> Coleen
>>>
>>> On 11/9/15 5:55 PM, Rachel Protacio wrote:
>>>> Hello,
>>>>
>>>> Please see my small changeset to add two develop levels to UL.
>>>>
>>>> Summary: This adds develop (that is, non-product) logging levels to 
>>>> the Unified Logging framework in order to support performance, 
>>>> footprint, and usefulness-of-output considerations while 
>>>> maintaining the ability for the user to specify levels of 
>>>> verbosity, i.e. default, "debug," and "trace" levels.
>>>> Open webrev: http://cr.openjdk.java.net/~rprotacio/8142366/
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8142366
>>>>
>>>> I tested the added levels locally with sample log messages to 
>>>> ensure proper functioning. When I convert future tags to logging 
>>>> with these levels, those tags will have their own tests and 
>>>> inherently exercise the added levels.
>>>>
>>>> Thank you,
>>>> Rachel
>>>
>>
>