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<p>What I'm saying is that detecting, and debugging, such issues is
vastly more difficult when the forgotten thread has been GC:ed.</p>
<div class="moz-cite-prefix">On 2026-01-12 12:31, Robert Engels
wrote:<br>
</div>
<blockquote type="cite" cite="mid:799A0CA7-8A87-4645-9761-8980835E1624@ix.netcom.com">
<div dir="ltr">No, just ensure that there is always a thread this
will eventually call unpark(). </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">You can ensure this with proper use of
try/finally. </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">If you write that code any nothing ever calls
unpark - it is hung (and leaked). You can resolve this without
any new APIs. </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">It has nothing to do with queues - it is all about
correctness. It seems queues (or channels) has been discussed
because this is a common source of this issue (especially in
Go). See #2 here: <a href="https://urldefense.com/v3/__https://oneuptime.com/blog/post/2026-01-07-go-goroutine-leaks/view__;!!ACWV5N9M2RV99hQ!Lc6RAKDcwT9pWlm7RR0zEh8Bw0kuCIHACWakPWcDKd89LJW1dwJMlK3Suc5v2grGe5E02hM6uJKJvH9m4PI$" moz-do-not-send="true">https://oneuptime.com/blog/post/2026-01-07-go-goroutine-leaks/view</a></div>
<div dir="ltr"><br>
<blockquote type="cite">On Jan 12, 2026, at 4:00 AM, Viktor
Klang <a class="moz-txt-link-rfc2396E" href="mailto:viktor.klang@oracle.com"><viktor.klang@oracle.com></a> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<p>In my example there is no queue. Are you suggesting that
all pre-existing code and all new code should get rewritten
using some new API?</p>
<div class="moz-cite-prefix">On 2026-01-11 18:57, robert
engels wrote:<br>
</div>
<blockquote type="cite" cite="mid:3C66E7C5-ABF7-4247-A88C-08683E7E2075@me.com">
<div dir="ltr">because if park wakes up, the thread already
has a reference to the queue meaning it can start another
thread that puts items into the queue. Meaning the queue
is not “unreferenceable”, so you can’t simply destroy a
thread waiting in park(). </div>
<div dir="ltr"><br>
<blockquote type="cite">On Jan 11, 2026, at 10:30 AM,
Viktor Klang <a class="moz-txt-link-rfc2396E" href="mailto:viktor.klang@oracle.com" moz-do-not-send="true"><viktor.klang@oracle.com></a>
wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<p>>This code is fundamentally broken. Park() can
wake up for any reason. <br>
<br>
I don't see how "When park wakes up" (i.e. the
temporal aspect) affects correctness in any way in the
example given.<br>
<br>
>I suggest you look at ClosableQueue - it is
correct and far easier to use. </p>
<p>The example is completely devoid of any queuing
concerns. We're talking about logic which is executed
by some thread, and the person who writes the code
does not strictly know whether that thread is a
platform thread, a pooled platform thread, a virtual
thread, an ephemeral virtual thread, a GC finalizer
thread.</p>
<p>In short, this is about: pre-existing code which may
get executed by an ephemeral virtual thread may <i>silently</i>
leak resources under certain circumstances. Now, it
can be argued that most of that code was "not ideal"
in the first place, but the big difference is that
when any such defect gets noticed in a running
application, there's a much better visibility if the
thread which ran into the problem is still there
(evidence) vs not (no evidence).</p>
<div class="moz-cite-prefix">On 2026-01-11 01:50, Robert
Engels wrote:<br>
</div>
<blockquote type="cite" cite="mid:1604DAB4-FCCA-4362-BAB9-22237B88AFF4@me.com">
<div dir="ltr">This code is fundamentally broken.
Park() can wake up for any reason. </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">I suggest you look at ClosableQueue -
it is correct and far easier to use. </div>
<div dir="ltr"><br>
<blockquote type="cite">On Jan 10, 2026, at 6:03 PM,
Viktor Klang <a class="moz-txt-link-rfc2396E" href="mailto:viktor.klang@oracle.com" moz-do-not-send="true"><viktor.klang@oracle.com></a>
wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<p>Hi Dmitry,<br>
<br>
An example can look like:<br>
<br>
void method() {<br>
long fileDescriptor =
acquireFileDescriptor();<br>
LockSupport.park();<br>
releaseFileDescriptor(fileDescriptor);<br>
}<br>
<br>
If an ephemeral VT executes that method, and
there are no other references to that ephemeral
VT, then at the point of park(), nothing can
unpark it anymore, and it will then never
release the file descriptor.<br>
<br>
<br>
><span style="white-space: pre-wrap">We generally don’t allow try blocks (providing other constructs), we also very strongly discourage (just a drop short of disallowing) ANY threading primitives.</span></p>
<p><br>
I don't see how that can work in practice,
because it requires all users of your constructs
to be familiar about exactly how all third-party
logic (including JDK classes) are implemented
under the hood. Perhaps I'm misunderstanding?<br>
<br>
</p>
<div class="moz-cite-prefix">On 2026-01-09 17:27,
Dmitry Zaslavsky wrote:<br>
</div>
<blockquote type="cite" cite="mid:5A5AEC77-43CC-4D2D-87E1-3EC6F8D066AF@gmail.com">
<pre wrap="" class="moz-quote-pre">Not sure what you mean by native resources?
Do you mean what people would use like try resources?
We generally don’t allow try blocks (providing other constructs), we also very strongly discourage (just a drop short of disallowing) ANY threading primitives.
Which makes me think that there is a better way to express my point from before.
I think there is actually a common pattern here.
We use VT inside of the lib. We don’t want users to actually use any threads all.
I think it’s a goal of Alex as well.
We use VT as a way to avoid using threads (if that makes sense).
I think ScopedTasks is going in the same direction. Ideally user just doesn’t know there are threads.
We use Scala (appealing to Victor ;)) vals and immutable collections is the norm.
We don’t want users to think about Threads period.
So the thought of "GC roots on a VT … we don’t want that though to ever occur or we failed ;)
</pre>
<blockquote type="cite">
<pre wrap="" class="moz-quote-pre">On Jan 9, 2026, at 10:26 AM, Viktor Klang <a class="moz-txt-link-rfc2396E" href="mailto:viktor.klang@oracle.com" moz-do-not-send="true"><viktor.klang@oracle.com></a> wrote:
On 2026-01-09 15:39, Dmitry Zaslavsky wrote:
</pre>
<blockquote type="cite">
<pre wrap="" class="moz-quote-pre">someCollection.apar.map { …. }
Can spin N tasks (Each can get it's VT) If some iteration of the loop throws, we don’t need to rest of the code to run, it’s costly.
If the task are not actively mounted but previously started and are waiting… (in our case it’s LockSupport.park) we just want to drop that entire queue and everything around it….
</pre>
</blockquote>
<pre wrap="" class="moz-quote-pre">How do you handle acquired native resources that are yet to be released?
--
Cheers,
√
Viktor Klang
Software Architect, Java Platform Group
Oracle
</pre>
</blockquote>
</blockquote>
<pre class="moz-signature" cols="72">--
Cheers,
√
Viktor Klang
Software Architect, Java Platform Group
Oracle</pre>
</div>
</blockquote>
</blockquote>
<pre class="moz-signature" cols="72">--
Cheers,
√
Viktor Klang
Software Architect, Java Platform Group
Oracle</pre>
</div>
</blockquote>
</blockquote>
<pre class="moz-signature" cols="72">--
Cheers,
√
Viktor Klang
Software Architect, Java Platform Group
Oracle</pre>
</div>
</blockquote>
</blockquote>
<pre class="moz-signature" cols="72">--
Cheers,
√
Viktor Klang
Software Architect, Java Platform Group
Oracle</pre>
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