When running a process I seem to unable to read more than 78643 chars. <p dir="aut

Three tips: if you know that you can have long lines, you need

Unnable to read more than 78643 chars from stdout pipe about processx HOT 3 OPEN

chwpearse commented on July 30, 2024

Unnable to read more than 78643 chars from stdout pipe

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Comments (3)

gaborcsardi commented on July 30, 2024

Three tips:

if you know that you can have long lines, you need to use read_output() instead of read_output_lines().
read_output() can always return less output than requested.
you need to call $poll_io() before reading, even if you call it with no waiting time: $poll_io(0).

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chwpearse commented on July 30, 2024

Ah thanks for that. For anyone who hits this problem in the future here's what I did:

proc_read_long_singleline <- function(proc, wait = 100, timeout = 5000){
  my_proc$poll_io(wait)
  counter <- 1
  output_lines_res <- proc$read_output_lines(1)
  output_res <- c()
  
  while(length(output_lines_res) == 0 & counter*wait <= timeout){
    output_res <- proc$read_output() %>% append(output_res, .)
    proc$poll_io(wait)
    counter <- counter + 1
    output_lines_res <- proc$read_output_lines(1) %>% append(output_lines_res, .)
  }
  
  res_output <- paste0(output_res, collapse = '') %>% paste0(output_lines_res)
}

if(exists('my_proc')){my_proc$kill()}
my_proc <- process$new(cmd_file, stdin = '|', stdout = '|', stderr = '|')
my_proc$write_input('\n')

read_chars <- my_proc %>% proc_read_long_singleline()

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gaborcsardi commented on July 30, 2024

I think this is documented, but I'll keep this issue open until we improve the documentation.

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