----------System.out:(11/837)----------
Process output: Exit code: 0
stdout: S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT CGC CGCT GCT
 0.0 0.0 0.0 0.0 15360.0 6144.0 115712.0 0.0 0.0 0.0 0.0 0.0 0 0.000 0 0.000 0 0.000 0.000
stderr:
Committed size of the pool 'Eden Space' is 15360
Committed size of the pool 'Eden Space' is 4096
Committed size of the pool 'Eden Space' is 3072
Process output: Exit code: 0
stdout: S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT CGC CGCT GCT
 0.0 0.0 0.0 0.0 3072.0 0.0 11264.0 2825.6 9472.0 9003.3 1024.0 845.3 26 0.204 3 0.292 1 0.000 0.497
stderr:
----------System.err:(15/1007)----------
java.lang.RuntimeException: Number of concurrent GC events is 1, but CGCT is 0
at utils.JstatResults.assertThat(JstatResults.java:172)
at utils.JstatGcResults.assertConsistency(JstatGcResults.java:118)
at GcTest01.main(GcTest01.java:59)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:569)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:115)
at java.base/java.lang.Thread.run(Thread.java:832)

JavaTest Message: Test threw exception: java.lang.RuntimeException: Number of concurrent GC events is 1, but CGCT is 0
JavaTest Message: shutting down test

If I'm reading things correctly JDK-8199519 changed the output to list a zero instead of a '-'. But now the test doesn't seem to like the zero - though I'm unclear on the exact failure circumstances.

Only seen on OS X so far.