RFR: 8324668: JDWP process management needs more efficient file descriptor handling [v4]

[David Holmes]

On Mon, 29 Jan 2024 10:00:37 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Can I please get a review of this change which proposes to address https://bugs.openjdk.org/browse/JDK-8324668?
>> 
>> This change proposes to fix the issue in jdwp where when launching a child process (for the `launch=<cmd>` option), it iterates over an extremely large number of file descriptors to close each one of those. Details about the issue and the proposed fixed are added in a subsequent comment in this PR https://github.com/openjdk/jdk/pull/17588#issuecomment-1912256075. tier1, tier2 and tier3 testing is currently in progress with this change.
>
> Jaikiran Pai has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - add a log message to help debuggability
>  - improve code comments
>  - David's review - use standard isdigit instead of custom isAsciiDigit

Updates look good to me. Thanks.

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PR Review: https://git.openjdk.org/jdk/pull/17588#pullrequestreview-1850352032