RFR: 8038925: Java 7 with G1 crashes in dump_instance_fields using jmap or jcmd without fullgc

[Thomas Schatzl]

Hi,

On Fri, 2014-04-25 at 14:17 +0200, Andreas Eriksson wrote:
> Hi,
> 
> Could I have a review for this G1 jdk7 only fix please?

  why is this change only necessary for jdk7?

> Description:
> When using G1 and doing a heap dump while no fullgc has been done, 
> hotspot crashes.
> This is because G1CollectedHeap::safe_object_iterate uses 
> ContiguousSpace::object_iterate_from, which does not avoid dead objects 
> that can still be on the heap when using G1.
> 
> The fix adds a G1 specific safe_object_iterate code path that avoids 
> dead objects.
> 
> http://cr.openjdk.java.net/~aeriksso/8038925/webrev.00/
> https://bugs.openjdk.java.net/browse/JDK-8038925
> 
> Thanks to Mikael Gerdin for his help with this.
> 

Thanks,
Thomas