RFR: 8214068: ZGC crashes with vmTestbase/nsk/jdi/ReferenceType/instances/instances004/TestDescription.java
per.liden at oracle.com
Wed Nov 21 13:21:46 UTC 2018
Thanks for reviewing, Robbin!
On 11/21/18 12:06 PM, Robbin Ehn wrote:
> On 2018-11-21 11:08, Erik Österlund wrote:
>> Hi Per,
>> Looks good.
> Ship it!
>> On 2018-11-21 10:11, Per Liden wrote:
>>> This patch adds a missing load barrier to the JVMTI heap walker. In
>>> VM_HeapWalkOperation::collect_simple_roots() the SimpleRootsClosure
>>> closure should not do raw loads of oops. Instead it should be loading
>>> them using NativeAccess<AS_NO_KEEPALIVE>::oop_load().
>>> This problem only affects ZGC, since it's (so far) the only collector
>>> that scans JNIHandles concurrently.
>>> The problem was easily reproducible when running
>>> However, for some reason this isn't reproducing in our CI pipeline,
>>> likely because of luck with timing. For example, this is harder to
>>> reproduce in a scenario where your using a smaller heap and hence
>>> have GC cycles happen more frequently.
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8214068
>>> Webrev: http://cr.openjdk.java.net/~pliden/8214068/webrev.0
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