Evaluate an R expression while collecting journals from completed futures

capture_journals(expr, substitute = TRUE, envir = parent.frame())

Arguments

expr: The R expression to evaluate
substitute: If TRUE, then expr is substituted, otherwise not.
envir: The environment where expr should be evaluated

Value

A list of FutureJournal:s.

Details

This function evaluates an R expression and capture the journals signaled by futures as they are completed. A future journal comprise a log of events appearing during the life-span of a future, e.g. the timestamps when the future was created, launched, queried, resolved, and its results are collected.

Examples

slow_fcn <- function(x) {
  Sys.sleep(x / 10)
  sqrt(x)
}

plan(multisession, workers = 2)
js <- capture_journals({
  fs <- lapply(3:1, FUN = function(x) future(slow_fcn(x)))
  value(fs)
})

## Summarize all journals
js_all <- Reduce(rbind, js)
print(summary(js_all), digits = 2L)
#> Number of futures: 3
#>   summary  evaluate evaluate_ratio  overhead overhead_ratio  duration  walltime
#> 1     min 0.10 secs           0.30 0.18 secs           0.53 0.35 secs 0.35 secs
#> 2    mean 0.23 secs           0.47 0.20 secs           0.41 0.48 secs 0.48 secs
#> 3  median 0.27 secs           0.51 0.20 secs           0.38 0.53 secs 0.53 secs
#> 4     max 0.30 secs           0.53 0.20 secs           0.36 0.57 secs 0.57 secs
#> 5   total 0.68 secs           0.47 0.59 secs           0.41 1.44 secs 1.44 secs

## Shut down parallel workers
plan(sequential)