RFR: 8214068: ZGC crashes with vmTestbase/nsk/jdi/ReferenceType/instances/instances004/TestDescription.java
Robbin Ehn
robbin.ehn at oracle.com
Wed Nov 21 11:06:23 UTC 2018
On 2018-11-21 11:08, Erik Österlund wrote:
> Hi Per,
>
> Looks good.
Ship it!
/Robbin
>
> Thanks,
> /Erik
>
> 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
>> vmTestbase/nsk/jdi/ReferenceType/instances/instances004/TestDescription.java.
>> 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
>>
>> /Per
>
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