Understood. Just trying to balance correctness with providing meaningful exceptions.
I suppose another approach is to let it all go deep and catch the error on the way back and provide the detail then. Not likely win any fans. 📱 > On May 30, 2020, at 12:30 PM, Martin Buchholz <marti...@google.com> wrote: > > I wrote an earlier version of this grow logic, and then it was > transplanted into other classes. > > We strongly suspect that the VM will throw OOME when we try to > allocate an array beyond MAX_ARRAY_SIZE, so are reluctant to do so, > but we also consider the VM behavior a bug that may eventually get > fixed (or is already a non-issue with a different VM). We are trying > for good behavior with both sorts of VM. > >> On Sat, May 30, 2020 at 7:32 AM Jim Laskey <james.las...@oracle.com> wrote: >> >> I'm working through https://bugs.openjdk.java.net/browse/JDK-8230744 >> <https://bugs.openjdk.java.net/browse/JDK-8230744> Several classes throw >> OutOfMemoryError without message . >> >> I'm wondering why hugeCapacity in >> src/jdk.zipfs/share/classes/jdk/nio/zipfs/ByteArrayChannel.java is defined as >> >> /** >> * The maximum size of array to allocate. >> * Some VMs reserve some header words in an array. >> * Attempts to allocate larger arrays may result in >> * OutOfMemoryError: Requested array size exceeds VM limit >> */ >> private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; >> >> /** >> * Increases the capacity to ensure that it can hold at least the >> * number of elements specified by the minimum capacity argument. >> * >> * @param minCapacity the desired minimum capacity >> */ >> private void grow(int minCapacity) { >> // overflow-conscious code >> int oldCapacity = buf.length; >> int newCapacity = oldCapacity << 1; >> if (newCapacity - minCapacity < 0) >> newCapacity = minCapacity; >> if (newCapacity - MAX_ARRAY_SIZE > 0) >> newCapacity = hugeCapacity(minCapacity); >> buf = Arrays.copyOf(buf, newCapacity); >> } >> >> private static int hugeCapacity(int minCapacity) { >> if (minCapacity < 0) // overflow >> throw new OutOfMemoryError(); >> return (minCapacity > MAX_ARRAY_SIZE) ? >> Integer.MAX_VALUE : >> MAX_ARRAY_SIZE; >> } >> >> It just seems that it's pushing the inevitable off to Arrays.copyOf. >> Shouldn't it be: >> >> private static int hugeCapacity(int minCapacity) { >> if (minCapacity < 0 || minCapacity > MAX_ARRAY_SIZE) { >> throw >> new OutOfMemoryError("ByteArrayChannel exceeds maximum size: >> " + >> MAX_ARRAY_SIZE); >> } >> >> return MAX_ARRAY_SIZE; >> } >> >> Real question: is there some hidden purpose behind this kind of logic? >> >> >> Cheers, >> >> -- Jim >> >>
