During some jtreg testing I got next failure on macos-x64 fastdebug:

command: main -XX:+UnlockDiagnosticVMOptions -XX:-UseUnalignedAccesses HeapByteBufferTest
reason: User specified action: run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:-UseUnalignedAccesses HeapByteBufferTest
elapsed time (seconds): 4.259
STDOUT:
STDERR:
java.lang.IndexOutOfBoundsException
at java.nio.Buffer.checkIndex(Buffer.java:546)
at java.nio.HeapByteBuffer.getShort(HeapByteBuffer.java:331)
at MyByteBuffer.getShort(HeapByteBufferTest.java:214)
at HeapByteBufferTest.step(HeapByteBufferTest.java:300)
at HeapByteBufferTest.run(HeapByteBufferTest.java:355)
at HeapByteBufferTest.main(HeapByteBufferTest.java:370)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)


I was not able to reproduce it. We need to use our random generator Utils.getRandomInstance() to know what seed to use for reproduction.
And also instead of random test all range of indexes.