RFR (s) 8059100: SIGSEGV VirtualMemoryTracker::remove_released_region

[Coleen Phillimore]

Thanks George!
Coleen

On 10/10/14, 3:04 PM, George Triantafillou wrote:
> Hi Coleen,
>
> Looks good.  Thanks for fixing this.
>
> -George
>
> On 10/10/2014 10:16 AM, Coleen Phillimore wrote:
>> Summary: Disallow increasing native memory tracking level
>>
>> There was support in the code for increasing NMT reporting level, 
>> which causes inconsistencies when called by multiple threads. There 
>> was also a shutdown() call in final_report() which turned NMT off 
>> while other threads could be running.  The final_report() function 
>> modified the running baseline in place but other threads calling NMT 
>> while it is running could see the wrong data.
>>
>> Made final_report() snapshot a baseline which is safe enough during 
>> error handling and not call shutdown().  Removed the reset() function 
>> because it's unnecessary at best, and at worst, dangerous to do to 
>> the running baseline.
>>
>> Also if final_report calls shutdown() it can hang getting the malloc 
>> site table lock if the error reported is in the malloc site table, 
>> while holding the lock.
>>
>> Tested with an aurora ad-hoc (thanks George) and linux-x64 testbase, 
>> jck and jtreg tests.  All with nmt=detail and PrintNMTStatistics.
>>
>> open webrev at http://cr.openjdk.java.net/~coleenp/8059100/
>> bug link https://bugs.openjdk.java.net/browse/JDK-8059100
>>
>> Thanks,
>> Coleen
>>
>