Two tests were seen failing in a recent CI job:

test/jdk/java/io/FileOutputStream/AtomicAppend.java failed with "6005 not equal to 10000"
----------System.out:(3/25)----------

Passed = 0, failed = 1

----------System.err:(28/1645)----------
6843 not equal to 10000
java.lang.Exception: Stack trace
at java.base/java.lang.Thread.dumpStack(Thread.java:1424)
at AtomicAppend.fail(AtomicAppend.java:68)
at AtomicAppend.fail(AtomicAppend.java:69)
at AtomicAppend.equal(AtomicAppend.java:74)
at AtomicAppend.test(AtomicAppend.java:59)
at AtomicAppend.instanceMain(AtomicAppend.java:78)
at AtomicAppend.main(AtomicAppend.java:76)
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.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:229)
at java.base/java.lang.Thread.run(Thread.java:831)
java.lang.AssertionError: Some tests failed
at AtomicAppend.instanceMain(AtomicAppend.java:80)
at AtomicAppend.main(AtomicAppend.java:76)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:569)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:229)
at java.base/java.lang.Thread.run(Thread.java:831)


test/jdk/java/nio/channels/FileChannel/AtomicAppend.java failed with "File not expected length".
java.lang.RuntimeException: File not expected length
at AtomicAppend.main(AtomicAppend.java:104)
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.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:229)
at java.base/java.lang.Thread.run(Thread.java:831)


In both cases the failures were observed on the same macosx-x64 machine. These failures could be unrelated, but it seems unlikely - hence only one bug until proven otherwise.