Adding help information to log tags

[Marcus Larsson]

This could be a good idea. Not all tags make sense in isolation though, 
but perhaps we can come up with at least some sort of description for 
these tags.

Thanks,
Marcus

On 01/13/2016 02:51 AM, Ioi Lam wrote:
> I have filed JDK-8146948: Add help information to log tags
>
> https://bugs.openjdk.java.net/browse/JDK-8146948
>
> - Ioi
>
> On 12/23/15 12:45 PM, Rachel Protacio wrote:
>> That seems like a good idea to me! It'd be helpful for the user and 
>> also anyone looking at the actual code in logTag.hpp
>> Rachel
>>
>> On 12/23/2015 12:19 AM, Ioi Lam wrote:
>>> Now there are a lot of log tags [1], and it looks like many more 
>>> will be added. I start to wonder what 'ihop' or 'rt' would do ...
>>>
>>> Would it make sense to add help information that can be printed to 
>>> the user, like
>>>
>>> #define LOG_TAG_LIST \
>>>   LOG_TAG(alloc,      "this prints something about alloc") \
>>>   LOG_TAG(age,        "blah blah") \
>>>
>>> $ java -Xlog:help=alloc
>>> alloc - this prints something about alloc
>>>
>>> $ java -Xlog:help=all
>>> alloc - this prints something about alloc
>>> age   - blah blah
>>>
>>>
>>> -----------------
>>>
>>> [1] The list of log tags as of today in jdk9/hs-rt/hotspot
>>>
>>> #define LOG_TAG_LIST \
>>>   LOG_TAG(alloc) \
>>>   LOG_TAG(age) \
>>>   LOG_TAG(barrier) \
>>>   LOG_TAG(bot) \
>>>   LOG_TAG(census) \
>>>   LOG_TAG(classhisto) \
>>>   LOG_TAG(classinit) \
>>>   LOG_TAG(comp) \
>>>   LOG_TAG(compaction) \
>>>   LOG_TAG(cpu) \
>>>   LOG_TAG(cset) \
>>>   LOG_TAG(defaultmethods) \
>>>   LOG_TAG(ergo) \
>>>   LOG_TAG(exceptions) \
>>>   LOG_TAG(exit) \
>>>   LOG_TAG(freelist) \
>>>   LOG_TAG(gc) \
>>>   LOG_TAG(heap) \
>>>   LOG_TAG(humongous) \
>>>   LOG_TAG(ihop) \
>>>   LOG_TAG(jni) \
>>>   LOG_TAG(liveness) \
>>>   LOG_TAG(logging) \
>>>   LOG_TAG(marking) \
>>>   LOG_TAG(metaspace) \
>>>   LOG_TAG(monitorinflation) \
>>>   LOG_TAG(phases) \
>>>   LOG_TAG(plab) \
>>>   LOG_TAG(promotion) \
>>>   LOG_TAG(ref) \
>>>   LOG_TAG(refine) \
>>>   LOG_TAG(region) \
>>>   LOG_TAG(remset) \
>>>   LOG_TAG(rt) \
>>>   LOG_TAG(safepoint) \
>>>   LOG_TAG(scavenge) \
>>>   LOG_TAG(scrub) \
>>>   LOG_TAG(start) \
>>>   LOG_TAG(state) \
>>>   LOG_TAG(stats) \
>>>   LOG_TAG(stringdedup) \
>>>   LOG_TAG(survivor) \
>>>   LOG_TAG(svc) \
>>>   LOG_TAG(sweep) \
>>>   LOG_TAG(task) \
>>>   LOG_TAG(tlab) \
>>>   LOG_TAG(time) \
>>>   LOG_TAG(verify) \
>>>   LOG_TAG(vmoperation)
>>>
>>>
>>
>