Timeouts in structured concurrency

[Holo The Sage Wolf]

I think having a static method that takes only the configFunc as a
parameter will be more than enough to satisfy both of my points.

And I indeed missed the last note in the javadoc regarding the first point.


On Thu, 18 Dec 2025, 23:00 David Alayachew, <davidalayachew at gmail.com>
wrote:

> For 1, the javadoc absolutely does help you. Please read for open.
>
>
> https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/concurrent/StructuredTaskScope.html#open()
>
> As for verbose, can you go into more detail? This is a traditional builder
> pattern addition, so it is literally 1 static method call.
>
> That said, if you dislike a 0 parameter call being forced into being a 2
> paramefer call when you need to add timeout, then sure, I think adding an
> overload for that static method that takes in the configFunction is
> reasonable. I'd support that.
>
>
> On Thu, Dec 18, 2025, 3:46 PM Holo The Sage Wolf <holo3146 at gmail.com>
> wrote:
>
>> Hello Loom devs,
>> Few years ago I experimented in a personal PoC project with
>> StructuredConcurrency in Java 19 and I had to stop working on it for
>> personal reasons.
>>
>> Recently I came back to the project and updated it to Java 25 and had to
>> change my code to the new way the API is built and while doing that I
>> noticed a couple of stuff I want to point out:
>>
>> 1. The default Joiner method can't receive timeout
>> Obviously that is wrong, but the API and JavaDoc don't actually help you.
>> Say you start with:
>>  ```java
>> try (var scope =  StructuredTaskScope.open()) {
>>     ...
>> }
>> ```
>> And I want to evolve the code to add timeout, I look at
>> the StructuredTaskScope static methods, and won't see any way to do that.
>> After reading a bit what StructuredTaskScope.open(Joiner, configFunction)
>> does, I will realise that I can set the timeout using the configFunction.
>> But then I will encounter the problem that I need to provide a Joiner,
>> currently the only way to actually get the "no args method"-joiner is to
>> look at the source code of the method, see which Joiner it uses and copy
>> that into my method to get:
>>  ```java
>> try (var scope =
>> StructuredTaskScope.open(Joiner.awaitAllSuccessfulOrThrow(), (conf) ->
>> ...)) {
>>     ...
>> }
>> ```
>> Not only is this a lot of work to do something very simple, there is a
>> high chance that people who start learning concurrency will want to use
>> timeout before they even know what the Joiner object is.
>>
>> 2. Changing only the timeout is "verbose".
>> I can only talk from my experience, so I may have the wrong impression,
>> but I feel like setting timeout is orders of magnitude more common than
>> changing the default ThreadFactory (especially when using virtual threads)
>> or setting a name.
>> I feel like adding a couple of overloads of the open method that takes
>> only an extra parameter of duration will be convenient:
>> > StructuredTaskScope.open()
>> > StructuredTaskScope.open(Duration timeout)
>> > StructuredTaskScope.open(Joiner joiner)
>> > StructuredTaskScope.open(Joiner joiner, Duration timeout)
>> > StructuredTaskScope.open(Joiner joiner, Function<Configuration,
>> Configuration> configFunction)
>>
>>
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