Experiencing an issue with ScheduledExecutorService alongside VT

[Yuval Lombard]

Hi Alan,

Thanks, sorry for the confusion, we also saw this odd release, and got read
of it, it was just a side note btw, because I realized I did not attach how
I have created my scheduler, so I elaborated on this as well.

Just to make sure by SPTE what exactly do you mean?

We are running into some difficulties now after upgrading to the latest EA
based on jdk24 where most of our utilized framework's libs are not
supporting it yet (Spring, and Spring-Boot)
So if there is an older available EA build based on jdk23 that may be
addressing one of the possible issues that may got us into this locking
state, we will be happy to test it.
Otherwise it will require some work from our end in order to try to package
our app


On Mon, 22 Jul 2024 at 10:46, Alan Bateman <Alan.Bateman at oracle.com> wrote:

> On 22/07/2024 07:09, Yuval Lombard wrote:
>
> Hi Alan,
>
> Thanks for the clarifications!
> OK regarding the pooling of the VT, now I understand what robert meant
> about the partial code example.
>
> The scheduler is created in this way:
> ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1)
> then as the code example shows after it is granted with a permit to
> execute a task, it delegates it to the VT by starting it this way:
> Thread.ofVirtual().start(() -> { ... }
>
>
> I read Robert's mail as a comment on the code fragment in your first mail.
> The finally block in that code fragment releases a permit unconditionally
> whereas I assume you only want to release if acquired in that thread.
>
> My comment is about thread dump you attached. Look at threads #73, #77 and
> #83 as examples. The stack traces suggests a SPTE using virtual threads as
> worker threads. It's nothing to do with the issue we are discussing here,
> just a comment that on a something surprising that you might want to look
> into.
>
> I upgrade the jdk to the latest EA and test it again, and get back to you
> in any case with the relevant thread dumps.
>
> Thanks. As I mentioned, I think this is related to preemption when
> cancelling a timer after Object.wait(millis). We may have to publish a new
> EA build.
>
> -Alan
>


-- 

Kind regards,

*Yuval Lombard*

*Lead Software Engineer*

+972.50.548.0111

yuval.l at securithings.com

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