RFR: 8294437: java/nio/channels/FileChannel tests slow on Windows [v5]

[Brian Burkhalter]

On Fri, 30 Sep 2022 20:25:27 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

>> Please review this test-only change that improves the execution speed of a few FileChannel tests:
>> - Transfer2GPlus, Transfer4GBFile, and TransferTo6GBFile were modified to use sparse files. Their speed is now consistent across platforms, provided that the platform / filesystem supports sparse files.
>> - LargeMapTest was rewritten to use sparse files, and to more precisely target the issue it was written to detect. In my tests it still crashed with EXCEPTION_ACCESS_VIOLATION when JDK-8286637 was reverted.
>> - MapTest: repetition was removed from `testForce` method; I'm not sure what issues it was supposed to catch, but at far as I can tell, it was only triggering timeouts, see [JDK-8289526](https://bugs.openjdk.org/browse/JDK-8289526), [JDK-8224480](https://bugs.openjdk.org/browse/JDK-8224480)
>
> Daniel Jeliński has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use try with resources

test/jdk/java/nio/channels/FileChannel/TransferTo6GBFile.java line 69:

> 67:             t1 - t0, TimeUnit.NANOSECONDS.toMillis(t1 - t0));
> 68: 
> 69:             // Setup looback connection and echo server

"looback" -> "loopback"

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PR: https://git.openjdk.org/jdk/pull/10464