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

[coleen.phillimore at oracle.com]

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?

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