Github user srowen commented on a diff in the pull request: https://github.com/apache/spark/pull/19460#discussion_r143570916 --- Diff: common/unsafe/src/main/java/org/apache/spark/unsafe/array/ByteArrayMethods.java --- @@ -40,6 +40,15 @@ public static int roundNumberOfBytesToNearestWord(int numBytes) { } } + // Some JVMs can't allocate arrays of length Integer.MAX_VALUE; actual max is somewhat smaller. + // Be conservative and lower the cap a little. + public static int MAX_ARRAY_LENGTH = Integer.MAX_VALUE - 8; + + // Use this value if the allocated byte arrays are used to store other types rather than bytes. + public static int maxWordRoundedArrayLength() { + return roundNumberOfBytesToNearestWord(MAX_ARRAY_LENGTH - 8); --- End diff -- Rounding won't do; it has to round _down_. I see that's why you wrote -8 here but it's a little confusing as -7 works more directly. And then, why bother? just write -15 in the constant above and explain.
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