Error: Cannot find progress bar (req_perform_parallel)

[JBGruber]

When I run a req_perform_parallel with a progress bar and abort the operation, every new call to req_perform_parallel will error until the R session is restarted. Here is a minimal example:

library(httr2)
reqs <- list(
  request(example_url()) |>
    req_url_path("/delay") |> 
    req_url_path_append(sample(1:10, 1))
) |>
  rep(100)

resps <- req_perform_parallel(reqs, progress = TRUE)

### stop with Esc ##
resps <- req_perform_parallel(reqs, progress = TRUE)
#> Error in cli::cli_progress_update(..., id = id) : 
#>   Cannot find progress bar `cli-25573-7`
#> Error in cli::cli_progress_update(..., id = id) : 
#>   Cannot find progress bar `cli-25573-7`

This does not apply to req_perform_sequential.

[hadley]

Hmmm create_progress_bar() should probably add an exit handler to the calling environment that automatically closes the progress bar. But I'm a bit surprised that's necessary because I don't understand why it would try and reuse the previous progress bar.

[JBGruber]

I also have no idea. And here is some more weirdness. I just noticed that it does not happen every time! If I hit Esc too fast, it does not seem to reuse the id???

Screencast_20241211_183723.webm

[hadley]

@gaborcsardi any idea what's going on here? The progress bar is created in a helper function:

httr2/R/utils.R

Lines 242 to 284 in e972770

	create_progress_bar <- function(total,
	name,
	config,
	env = caller_env(),
	config_arg = caller_arg(config),
	error_call = caller_env()) {
	if (is_false(config)) {
	return(list(
	update = function(...) {},
	done = function() {}
	))
	}
	if (is.null(config) || is_bool(config)) {
	args <- list()
	} else if (is_scalar_character(config)) {
	args <- list(name = config)
	} else if (is.list(config)) {
	args <- config
	} else {
	stop_input_type(
	config,
	what = c("a bool", "a string", "a list"),
	arg = config_arg,
	call = error_call
	)
	}
	args$name <- args$name %||% name
	# Can be removed if https://github.com/r-lib/cli/issues/630 is fixed
	if (is.infinite(total)) {
	total <- NA
	}
	args$total <- total
	args$.envir <- env
	id <- exec(cli::cli_progress_bar, !!!args)
	list(
	update = function(...) cli::cli_progress_update(..., id = id),
	done = function() cli::cli_progress_done(id = id)
	)
	}

Maybe something is going wrong with how I set .envir?

[gaborcsardi]

I am not sure, but my guess is that the progress bar's env is already removed, but the curl multi-handle is still alive and you get a final update() call for it.

[hadley]

Ooooh I bet that's it.

[hadley]

I think we can fix this by using a separate pool for each req_perform_parallel() call, rather than relying on the default global pool.

[gaborcsardi]

I think you can also tryCatch() and ignore the error.