GitHub user sksamuel opened a pull request:
https://github.com/apache/spark/pull/5376
Replace use of .size with .length for Arrays
Invoking .size on arrays is valid, but requires an implicit conversion to
SeqLike. This incurs a compile time overhead and more importantly a runtime
overhead, as the Array must be wrapped before the method can be invoked. For
example, the difference in generated byte code is:
public int withSize();
Code:
0: getstatic #23 // Field
scala/Predef$.MODULE$:Lscala/Predef$;
3: aload_0
4: invokevirtual #25 // Method array:()[I
7: invokevirtual #29 // Method
scala/Predef$.intArrayOps:([I)Lscala/collection/mutable/ArrayOps;
10: invokeinterface #34, 1 // InterfaceMethod
scala/collection/mutable/ArrayOps.size:()I
15: ireturn
public int withLength();
Code:
0: aload_0
1: invokevirtual #25 // Method array:()[I
4: arraylength
5: ireturn
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sksamuel/spark master
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/5376.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #5376
----
commit 77ec261c9c6052d7f5f46fe90a5384aee0c0c362
Author: sksamuel <[email protected]>
Date: 2015-04-06T21:18:24Z
Replace use of .size with .length for Arrays.
Invoking .size on arrays is valid, but requires an implicit conversion to
SeqLike. This incurs a compile time overhead and more importantly a runtime
overhead, as the Array must be wrapped before the method can be invoked. For
example, the difference in generated byte code is:
public int withSize();
Code:
0: getstatic #23 // Field
scala/Predef$.MODULE$:Lscala/Predef$;
3: aload_0
4: invokevirtual #25 // Method array:()[I
7: invokevirtual #29 // Method
scala/Predef$.intArrayOps:([I)Lscala/collection/mutable/ArrayOps;
10: invokeinterface #34, 1 // InterfaceMethod
scala/collection/mutable/ArrayOps.size:()I
15: ireturn
public int withLength();
Code:
0: aload_0
1: invokevirtual #25 // Method array:()[I
4: arraylength
5: ireturn
----
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