java / expert
Snippet
Structured Concurrency with StructuredTaskScope
Structured Task Scope (Preview in Java 21+) treats groups of related tasks running in different threads as a single unit of work. ShutdownOnFailure ensures that if one subtask fails, all other related virtual threads are automatically cancelled, preventing 'orphan' threads and improving observability.
snippet.java
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try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {Supplier<String> user = scope.fork(() -> fetchUser(id));Supplier<Integer> order = scope.fork(() -> fetchOrder(id));scope.join().throwIfFailed();return new Dashboard(user.get(), order.get());}
Breakdown
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new StructuredTaskScope.ShutdownOnFailure()
Creates a scope that shuts down all forks if any single fork fails.
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scope.fork(() -> ...)
Starts a subtask in a new virtual thread within the current scope.
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scope.join().throwIfFailed()
Waits for all forks to finish and propagates the first exception if any occurred.