RFR (s) 8059100: SIGSEGV VirtualMemoryTracker::remove_released_region

[Coleen Phillimore]

Thank you Christian!
Coleen

On 10/10/14, 2:47 PM, Christian Tornqvist wrote:
> Hi Coleen,
>
> This looks good, thanks for fixing this.
>
> Thanks,
> Christian
>
> -----Original Message-----
> From: hotspot-runtime-dev
> [mailto:hotspot-runtime-dev-bounces at openjdk.java.net] On Behalf Of Coleen
> Phillimore
> Sent: Friday, October 10, 2014 10:17 AM
> To: hotspot-runtime-dev
> Subject: RFR (s) 8059100: SIGSEGV
> VirtualMemoryTracker::remove_released_region
>
> 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
>
>