Evaluate an R expression while collecting journals from completed futures

Usage

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
#> 1     min 0.11 secs           0.18 0.017 secs          0.029 0.59 secs
#> 2    mean 0.29 secs           0.43 0.215 secs          0.321 0.67 secs
#> 3  median 0.33 secs           0.47 0.027 secs          0.038 0.70 secs
#> 4     max 0.43 secs           0.60 0.599 secs          0.839 0.71 secs
#> 5   total 0.87 secs           0.43 0.644 secs          0.321 2.00 secs
#>    walltime
#> 1 0.59 secs
#> 2 0.67 secs
#> 3 0.70 secs
#> 4 0.71 secs
#> 5 2.00 secs

## Shut down parallel workers
plan(sequential)