Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/14762#discussion_r78986374
--- Diff:
common/unsafe/src/main/java/org/apache/spark/unsafe/array/ByteArrayMethods.java
---
@@ -47,13 +47,20 @@ public static int roundNumberOfBytesToNearestWord(int
numBytes) {
public static boolean arrayEquals(
Object leftBase, long leftOffset, Object rightBase, long
rightOffset, final long length) {
int i = 0;
- while (i <= length - 8) {
- if (Platform.getLong(leftBase, leftOffset + i) !=
- Platform.getLong(rightBase, rightOffset + i)) {
- return false;
- }
- i += 8;
- }
+
+ // This attempts to speed up the memcmp type of operation, but there
is no way
+ // to guarantee that the offsets will be on a word boundary in order
to use
+ // Platform.getLong
--- End diff --
But they'll be at the same offset 1/8th of the time and then you can
compare byte by byte at the start until you reach a word boundary (the reverse
of what happens at the end).
Yes, at least the current behavior shouldn't be changed for non-SPARC.
You raise a good point, that maybe making the long word accesses aligned on
non-SPARC is a good idea anyway?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
