New Early Access builds

[Christian Stein]

Hi Loom team, Hi Alan,

The latest Loom EA build (openjdk-16-loom+9-316_linux-x64_bin.tar.gz)
loaded and installed flawlessly [1] on the GitHub Actions environment.

The recorded timings look promising as well. Will update the table
displayed on the project's README.md, soon.

The run with 1,000,000 virtual threads emitted some warnings, though.
They read like:

  Warning: [warning][os,thread] Failed to start thread -
    pthread_create failed (EAGAIN) for
    attributes: stacksize: 1024k, guardsize: 0k, detached.

Are those memory-related issues?

The program logic (only Thread.sleep() here) doesn't seem
to be affected by those warnings.

Cheers,
Christian

[1] https://github.com/sormuras/junit5-looming/runs/1479126987
[2] https://github.com/sormuras/junit5-looming/runs/1479126987#step:10:15

On Tue, Dec 1, 2020 at 10:16 AM Alan Bateman <Alan.Bateman at oracle.com>
wrote:

>
> The builds at the Project Loom Early Access page [1] have been
> refreshed. The latest builds are based on jdk-16+25 (JDK 16 build 25).
>
> There are important stability fixes in this build. We think this build
> should resolve most of the crashes that people have reported over the
> last few months when running with concurrent GCs. We are mostly testing
> with G1 and ZGC.  There may be a small performance impact in some cases
> with the changes but for now, it will be great if you have been seeing
> issues to re-test to see if there are any other issues.
>
> One area that is currently not stable is the debugger support. We are
> mid way through a big re-implementation. The "new approach" upgrades JVM
> TI to fully support virtual threads so that the suspend/resume policies
> needed when debugging can be supported. It also avoids the thread
> identity issues that plagued the original approach. We hope to be at the
> point soon where we can engage with the IDE/debugger maintainers about
> adding support for virtual threads. We expect debuggers will need modest
> changes, esp. in areas where a debugger wants to track all threads or
> enumerate all threads or thread groups.
>
> -Alan
>
> [1] http://jdk.java.net/loom/
>