Integrated: 8287496: Alternative virtual thread implementation that maps to OS thread

[Alan Bateman]

On Sun, 29 May 2022 14:46:39 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> This patch adds an alternative virtual thread implementation where each virtual thread is backed by an OS thread. It doesn't scale but it can be used by ports that don't have continuations support in the VM. Aside from scalability, the lack of continuations support means:
> 
> 1. JVM TI is not supported when running with --enable-preview (the JVM TI spec allows for this) 
> 2. jshell --enable-preview can't be used (as jshell uses the debugger APIs and so needs JVM TI)
> 
> The VM option "VMContinuations" is added as an experimental option so it can be used by tests. A number of tests are changed to re-run with -XX:-VMContinuations. A new jtreg property is added so that tests that need the underlying VM support to be present can use "@requires vm.continuations" in the test description. A follow-up change would be to add "@requires vm.continuations" to the ~70 serviceability/jvmti/vthread that run with preview features enabled.

This pull request has now been integrated.

Changeset: 6ff2d89e
Author:    Alan Bateman <alanb at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/6ff2d89ea11934bb13c8a419e7bad4fd40f76759
Stats:     747 lines in 72 files changed: 574 ins; 53 del; 120 mod

8287496: Alternative virtual thread implementation that maps to OS thread

Reviewed-by: rehn, mchung

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PR: https://git.openjdk.java.net/jdk/pull/8939