[jdk21u] RFR: 8312127: FileDescriptor.sync should temporarily increase parallelism

[Alan Bateman]

On Thu, 10 Aug 2023 16:06:10 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Clean backport to avoid the temporary loss of platform thread when virtual thread does `fsync`. In https://github.com/openjdk/jdk/pull/15231, I tested that the overhead of doing this for platform threads is very small compared to the cost of the `fsync` itself.

I also had this on my list for jdk21u, looks good.

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Marked as reviewed by alanb (Reviewer).

PR Review: https://git.openjdk.org/jdk21u/pull/52#pullrequestreview-1573573300