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

Andreas Eriksson andreas.eriksson at oracle.com
Wed May 21 09:36:47 UTC 2014

Thanks Mikael.

Could I have a review from a jdk7u Reviewer as well please?


On 2014-05-21 10:46, Mikael Gerdin wrote:
> Hi Andreas,
> On Tuesday 20 May 2014 16.26.40 Andreas Eriksson wrote:
>> Hi,
>> Could I have a review for this G1 jdk7 only fix please?
>> (There is a related problem in jdk8 and jdk9, where an assert can fail
>> because of this problem. I have logged another bug for this.)
>> Description:
>> Due to the marking cleanup reclaiming empty regions, and having stale
>> references a crash can occur when doing a heap dump.
>> The code tries to do an is_klass check on the object, which crashes the VM.
>> The fix is to add an is_perm check before doing the check, since is_perm
>> will do a bounds check on the oop and if it's in the perm gen we know
>> it's safe to look at it since G1 only ever does full compactions of the
>> perm gen.
>> For more information, and a more in-depth analysis, please see the jira bug.
>> http://cr.openjdk.java.net/~aeriksso/8038925/webrev.01/
> The change looks good to me.
> /Mikael
>> https://bugs.openjdk.java.net/browse/JDK-8038925
>> Regards,
>> Andreas

More information about the hotspot-gc-dev mailing list