RFR: CODETOOLS-7903091: Convert jtreg to use NIO

[Jonathan Gibbons]

On Tue, 8 Feb 2022 07:28:08 GMT, Iris Clark <iris at openjdk.org> wrote:

> I think this is a great first pass at modernizing jtreg! I only had a few minor comments.
> 
> Due to the nature of this change, I'd be reluctant to recommend cutting over to this version of jtreg without wide communication and extensive testing on the existing test suite. For testing, minimally, you should confirm that, for a given set of tests, you have the same number of pass/fail tests using both the old and new versions of the tool and the failures themselves are consistent (i.e. test failures occur because of the same problem in the system, not jtreg file/path handling). Recommend that this test be repeated across multiple platforms.

Thanks for the review.  Yes, the next step is multi-platform use for JDK tier1 and maybe tier2 test runs, especially including Windows. The good news is that for many/most of the bigger changes (Locations, SearchPath, TestManager, ExtraPropDefns, etc) to `jtreg` over the past many years, we have moderately good targeted jtreg self-tests. It is worth noting (forgot to mention this earlier) that only one of these self-tests had to be modified because of the changes ... the venerable `Basic.java`, which accesses `jtreg` internal API; all other tests continue to pass without modification.

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PR: https://git.openjdk.java.net/jtreg/pull/50