cancel: Cancel a future

In future: Unified Parallel and Distributed Processing in R for Everyone

Cancel a future

Description

Cancels futures, with the option to interrupt running ones.

Usage

cancel(x, interrupt = TRUE, ...)

Arguments

x	A Future.
interrupt	If TRUE, running futures are interrupted, if the future backend supports it.
...	All arguments used by the S3 methods.

Value

cancel() returns (invisibly) the canceled Futures after flagging them as "canceled" and possibly interrupting them as well.

Canceling a lazy or a finished future has no effect.

See Also

A canceled future can be reset() to a lazy, vanilla future such that it can be relaunched, possible on another future backend.

Examples

## Set up two parallel workers
plan(multisession, workers = 2)

## Launch two long running future
fs <- lapply(c(1, 2), function(duration) {
  future({
    Sys.sleep(duration)
    42
  })
})

## Wait until at least one of the futures is resolved
while (!any(resolved(fs))) Sys.sleep(0.1)

## Cancel the future that is not yet resolved
r <- resolved(fs)
cancel(fs[!r])

## Get the value of the resolved future
f <- fs[r]
v <- value(f)
message("Result: ", v)

## The value of the canceled future is an error
try(v <- value(fs[!r]))

## Shut down parallel workers
plan(sequential)

future documentation built on June 8, 2025, 10:09 a.m.