Bug ID: JDK-8294437 java/nio/channels/FileChannel tests slow on Windows

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JDK 20
20 b18Fixed

The following tests take much longer to execute on Windows, as compared to other platforms:
java/nio/channels/FileChannel/TransferTo6GBFile.java - 91 seconds
java/nio/channels/FileChannel/Transfer4GBFile.java - 85 seconds
java/nio/channels/FileChannel/Transfer2GPlus.java - 85 seconds

On other platforms the same tests complete under a second.
The tests are run in exclusive mode, which means that they are never run in parallel, which slows down tier2 testing even more.

We can probably speed up these tests by making sure that the test files are created with StandardOpenOption.SPARSE.

Changeset: a4f2078b Author: Daniel Jeliński <djelinski@openjdk.org> Date: 2022-10-03 17:42:56 +0000 URL: https://git.openjdk.org/jdk/commit/a4f2078bd60d06795099c52ca8d437a8128eb8f6
03-10-2022
A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/10464 Date: 2022-09-28 10:58:43 +0000
28-09-2022
one more test to examine: java/nio/channels/FileChannel/LargeMapTest.java - 172 seconds it's slow on all platforms, but again much slower on Windows, and could see some improvement from sparse files
28-09-2022
[~alanb] I chatted with Brian briefly; he said he was not looking into these tests at the moment, and I could take them if I wanted to.
27-09-2022
[~djelinski] Can you check with [~bpb] as I think he is already looking to changing these tests to use sparse files.
27-09-2022
Thanks. One other thing is that I think the tests run with exclusive.dirs set so that they don't running concurrently with each other. This has a bit impact on macOS systems with HDD. The tests will of course run concurrently with tests in other directories.
27-09-2022