Task cancellation

Call cancel() when work is no longer useful, but design for the possibility that it has already started. Whether Pyroxide can stop it depends on its state and execution boundary.

Task state and mode	`cancel()`	Outcome
Pending, any mode	`True`	Work is skipped; status becomes `Cancelled`
Running, isolated	`True` after termination	Worker process is terminated; status becomes `Cancelled`
Running, in-process Python	`False`	Callable continues and its real result is preserved
Running, in-process WASM or native	`False`	Guest or native call continues
Terminal	`False`	Status and result remain unchanged

handle = task_function(payload)
if handle.cancel():
    print("Cancellation took effect")
else:
    print("The task may already be running or finished")

Calling result() on a cancelled task raises RuntimeError("Task cancelled").

Python threads, foreign native calls, and a running WASM invocation cannot be interrupted safely at an arbitrary instruction. Use cooperative cancellation inside your callable when you need finer control, or use isolated=True when process termination is acceptable.

WASM execution timeouts are separate from user cancellation. They trap a guest after its epoch deadline; see WebAssembly.

A timeout passed to result() or result_async() also stops only the wait; it does not cancel the task. See Getting started for handle lifetime after a timeout.

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Pyroxide User Manual

Task cancellation