StructuredTaskScope.TimeoutException vs UncheckedTimeoutException

[Alan Bateman]

On 21/10/2025 13:50, Pavel Rappo wrote:
> As suggested in a PR thread [*], I bring this question to loom-dev:
>
> I haven't been paying much attention to the recent previews of this
> feature, so feel free to point me to a relevant discussion elsewhere.
>
> As I understand it, an unchecked StructuredTaskScope.TimeoutException
> was added in JDK 25. There's also the well-known checked
> java.util.TimeoutException. I assume that the namesake exception was
> added solely because it's unchecked. I also assume
> UncheckedTimeoutException was considered at some stage, because in my
> mind, the situation is similar to that of
> IOException/UncheckedIOException.

If a timeout is configured when opening a new StructuredTaskScope then 
it applies to the scope. If the timeout expires before the scope is 
closed then the timeout causes the scope to be cancelled and join to 
wakeup. Declaring join to throw the checked-TimeoutException would be 
very annoying when not using a timeout or in the update, when there is 
other outcome when the timeout expires.

One of these years, there will be progress on the topic of exception 
transparency. It's impossible to know how this might look but there is a 
good chance that it will shine a light on past decisions to introduce 
UncheckedXXX exceptions. Introducing UncheckedTimeoutException would 
invite more usages, way beyond the very specific need here.

-Alan
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