Withdrawn: 8337199: Add jcmd Thread.vthread_summary diagnostic command

[duke]

On Thu, 14 Nov 2024 21:34:08 GMT, Larry Cable <duke at openjdk.org> wrote:

> c.f: [https://bugs.openjdk.org/browse/JDK-8339420](https://bugs.openjdk.org/browse/JDK-8339420)
> 
> Summary
> -------
> 
> Add `jcmd <pid> Thread.vthread_summary` to print summary information that is useful when trying to diagnose issues with virtual threads.
> 
> 
> Problem
> -------
> 
> The JDK is lacking tooling to diagnose issues with virtual threads.
> 
> 
> Solution
> --------
> 
> Add a new command that the `jcmd` command line tool can use to print information about virtual threads. The output includes the virtual thread scheduler, the schedulers used to support timeouts, and the I/O pollers used to support virtual threads doing socket I/O, and a summary of the thread groupings.
> 
> Here is sample output. The output is intended for experts and is not intended for automated parsing.
> 
> 
> Virtual thread scheduler:
> java.util.concurrent.ForkJoinPool at 4a624db0[Running, parallelism = 16, size = 2, active = 0, running = 0, steals = 2, tasks = 0, submissions = 0]
> 
> Timeout schedulers:
> [0] java.util.concurrent.ScheduledThreadPoolExecutor at 1f17ae12[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
> [1] java.util.concurrent.ScheduledThreadPoolExecutor at 6193b845[Running, pool size = 1, active threads = 0, queued tasks = 1, completed tasks = 0]
> [2] java.util.concurrent.ScheduledThreadPoolExecutor at c4437c4[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
> [3] java.util.concurrent.ScheduledThreadPoolExecutor at 3f91beef[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
> 
> Read I/O pollers:
> [0] sun.nio.ch.KQueuePoller at 524bf25 [registered = 1]
> 
> Write I/O pollers:
> [0] sun.nio.ch.KQueuePoller at 25c41da2 [registered = 0]
> 
> Thread groupings:
> <root> [platform threads = 11, virtual threads = 0]
> java.util.concurrent.ScheduledThreadPoolExecutor at c4437c4 [platform threads = 0, virtual threads = 0]
> java.util.concurrent.ScheduledThreadPoolExecutor at 3f91beef [platform threads = 0, virtual threads = 0]
> ForkJoinPool.commonPool/jdk.internal.vm.SharedThreadContainer at 4fa374ea [platform threads = 0, virtual threads = 0]
> java.util.concurrent.ThreadPoolExecutor at 506e1b77 [platform threads = 1, virtual threads = 0]
> java.util.concurrent.ScheduledThreadPoolExecutor at 1f17ae12 [platform threads = 0, virtual threads = 0]
> java.util.concurrent.ThreadPerTaskExecutor at 24155ffc [platform threads = 0, virtual threads = 2]
> ForkJoinPool-1/jdk.internal.vm.SharedThreadContainer at 48a03463 [platform threads = 2, virtual threads = 0]
> java.util.concurrent.Scheduled...

This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk/pull/22121