RFR (XS) 8208251: serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorGCCMSTest.java fails intermittently on Linux-X64

[Daniel D. Daugherty]

On 7/26/18 12:53 PM, JC Beyler wrote:
> Hi all,
>
> As we fixed the HeapMonitorTest to not fail from time to time, there 
> seems to be the same issue and risk in HeapMonitorGCTest. Could 
> someone review the similar fix:
>
> Webrev: http://cr.openjdk.java.net/~jcbeyler/8208251/webrev.00/ 
> <http://cr.openjdk.java.net/%7Ejcbeyler/8208251/webrev.00/>

test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorGCTest.java
     No comments.

Thumbs up!

Perhaps consider filing a bug to refactor HeapMonitorTest and
HeapMonitorGCTest.java so that they share code... then we won't
have to fix the same bug in two places...

Dan


> Bug: https://bugs.openjdk.java.net/browse/JDK-8208251
>
> The risk is that the last interval is too big and no sampled object is 
> live after the allocation method. If a GC happens before the check for 
> sample code, it is possible no live objects still exist.
>
> The solution is to reduce the sampling interval to make it highly 
> unlikely for no samples to happen in any allocation iteration, keeping 
> at least one sampled object live. But also check the GC'd objects in 
> the system in case they did actually all already get GC'd.
>
> Thanks,
> Jc

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