[External] : Re: Ephemeral threads

[Remi Forax]

It starts to be off topic, 
but it's not clear to me that in Java we want to map a generator to an iterator and not to stream (a push iterator with a cleanup semantics). 

regards, 
Rémi 

> From: "Alex Otenko" <oleksandr.otenko at gmail.com>
> To: "Alan Bateman" <alan.bateman at oracle.com>
> Cc: "loom-dev" <loom-dev at openjdk.org>
> Sent: Tuesday, January 13, 2026 10:28:13 AM
> Subject: Re: [External] : Re: Ephemeral threads

> Yes, I understand that now that's not easy to do in Java. I just don't think
> it's all that exotic, and certainly not a bug. After all, we've all written at
> least one iterator when we did a coding interview.

> There is 1:1 correspondence between the iterators and the generators. So if we
> can GC the iterators without special dance, we should be able to do that for
> the generators. You could see an iterator as an explicit declaration that you
> are not going to use any features that rely on there being a finally - no
> unlocking, no resource management outside of what a finalizer can achieve, no
> peer to coordinate with, etc. Likewise an explicit declaration by an engineer
> that this here piece of code entering a wait is perfectly fine to GC, doesn't
> seem all that different.

> Yes, in general there are thread semantics, try-finally, reference loops and
> other obstacles - but we don't need to solve a general case, just the one that
> is in 1:1 correspondence with the iterators.

> I understand that there may be safe ways to implement the same with the existing
> mechanisms - like, the user of the generator might wrap the interaction in a
> try-with-resource, and that way control the lifecycle explicitly.

> On Tue, 13 Jan 2026, 08:00 Alan Bateman, < [ mailto:alan.bateman at oracle.com |
> alan.bateman at oracle.com ] > wrote:

>> On 13/01/2026 06:42, Alex Otenko wrote:

>> > I think there are plenty of designs with generators, iterators and
>> > async where non-termination is not a bug.

>> That is true is some other languages/runtimes. If Java were to add
>> generators or some other exotic control flow in the future then there
>> would be more spooky issues to work through, some of which overlap with
>> the spooky issues that have come up in the discussion here.

>> -Alan
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