RFR (S) 6909265: assert(_OnDeck != Self->_MutexEvent, "invariant") with -XX:+PrintMallocFree

[coleen.phillimore at oracle.com]

On 2/1/18 9:00 AM, Zhengyu Gu wrote:
>
>
> On 02/01/2018 08:37 AM, coleen.phillimore at oracle.com wrote:
>>
>>
>> On 1/31/18 10:36 PM, David Holmes wrote:
>>> Hi Coleen,
>>>
>>> On 1/02/2018 1:01 PM, coleen.phillimore at oracle.com wrote:
>>>> Summary: Convert to logging without thread locking
>>>>
>>>> There are two options (-XX:+PrintMallocFree and -XX:+PrintMalloc) 
>>>> to print the calls and memory returned in malloc and free calls in 
>>>> the vm. I converted the first one to Unified Logging which doesn't 
>>>> crash getting the tty lock in the Thread destructor and removed the 
>>>> latter.  I don't see the usefulness of this logging honestly, so if 
>>>> the opinion is to remove this logging, I'd be happy to do so. NMT 
>>>> seems much more useful.
>>>
>>> I'm not sure about this one. Arguably some interesting malloc/frees 
>>> occur before log configuration.
>>
>> They also occurred before tty initialization and afterward too.
>>>
>>> That aside, given you always seem to do:
>>>
>>> log_is_enabled(Trace, malloc, free)
>>>
>>> which requires
>>>
>>> -Xlog:malloc+free=trace
>>>
>>> would it make more sense to define a single tag eg mallocfree or 
>>> nativemem or ???
>>>
>>
>> It's an opinion question.  I picked this to match the option and 
>> assume one would want to see both mallocs and frees.  I like the 
>> composition of small tags that have meaning.  Then again, I could 
>> change it if you have an opinion about this.
>>> Or, as you say, just drop this altogether. Is it useful for when 
>>> debugging NMT?
>>>
>>
>> I doubt it's useful for debugging NMT.  It might have been useful 
>> once but I don't know why.  What's your opinion?
>
> No, I never used this to debug NMT. It just generates too much data to 
> be useful, I vote to remove it all together.

Thank you, Zhengyu.  I agree with you.  We'll wait to see what David (or 
anyone else that wants to save this logging) thinks.

Coleen
>
> Thanks,
>
> -Zhengyu
>
>
>>
>> thanks,
>> Coleen
>>
>>> Thanks,
>>> David
>>>
>>>> Tested with NMT and tier1 tests, and wrote test.
>>>>
>>>> open webrev at http://cr.openjdk.java.net/~coleenp/6909265.01/webrev
>>>> bug link https://bugs.openjdk.java.net/browse/JDK-6909265
>>>>
>>>> Thanks,
>>>> Coleen
>>