[ 
https://issues.apache.org/jira/browse/ARROW-15730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17496336#comment-17496336
 ] 

Jameel Alsalam commented on ARROW-15730:
----------------------------------------

Hello, I think I have reproduced the issue here. About 1.5 GB appears to still 
be in use after the remove statement. I am on CRAN arrow 7.0.0. I was 
interested in this issue because I have tried to diagnose a different arrow 
memory issue involving write_dataset. In my investigations, the memory reported 
internally by gc() or arrow is quite different than what is reported by Windows 
via e.g., task manager. I have found a way to get the system task manager-like 
memory by running: `system2("tasklist", stdout=TRUE)` and then filtering for 
the right process. Pasted below I ran your script with the additional memory 
info.

 

``` r
library(arrow)
#> 
#> Attaching package: 'arrow'
#> The following object is masked from 'package:utils':
#> 
#>     timestamp

print_memory <- function() {
  print(sprintf("Arrow: %s MB", trunc(arrow_info()$memory$bytes_allocated / 
1024 / 1024)))
  print(sprintf("R: %s MB", gc()["Vcells", 2]))
  print((function(t) t[grep(Sys.getpid(), t)])(system2("tasklist", stdout = 
TRUE)))
}

# Create example data
size <- 1E8

print_memory()
#> [1] "Arrow: 0 MB"
#> [1] "R: 9.8 MB"
#> [1] "Rterm.exe                    19096 Console                    2    
125,672 K"

my_table <- arrow_table(
  x = Array$create(sample(letters, size, replace = TRUE)),
  y = Array$create(as.factor(sample(letters, size, replace = TRUE))),
  z = Array$create(as.Date(1:size, as.Date("2020-01-01"))),
  a = Array$create(1:size, type=int32())
)

arrow::write_arrow(my_table, "file.arrow5")
#> Warning: Use 'write_ipc_stream' or 'write_feather' instead.
remove(my_table)

# Note: you may need to wait a few seconds for Arrow memory pool to free memory
Sys.sleep(5)
print_memory()
#> [1] "Arrow: 953 MB"
#> [1] "R: 392.6 MB"
#> [1] "Rterm.exe                    19096 Console                    2    
563,344 K"


options(arrow.use_threads=FALSE);

arrow::set_cpu_count(1); # need this - otherwise it freezes under windows

table <- arrow::read_arrow('file.arrow5')
#> Warning: Use 'read_ipc_stream' or 'read_feather' instead.
print_memory()
#> [1] "Arrow: 1335 MB"
#> [1] "R: 1156.2 MB"
#> [1] "Rterm.exe                    19096 Console                    2  
2,709,252 K"

remove(table)
Sys.sleep(5)
print_memory()
#> [1] "Arrow: 858 MB"
#> [1] "R: 11.8 MB"
#> [1] "Rterm.exe                    19096 Console                    2  
1,534,436 K"
```

<sup>Created on 2022-02-22 by the [reprex 
package](https://reprex.tidyverse.org) (v2.0.1)</sup>

<details style="margin-bottom:10px;">
<summary>
Session info
</summary>

``` r
sessioninfo::session_info()
#> - Session info 
---------------------------------------------------------------
#>  setting  value
#>  version  R version 4.0.5 (2021-03-31)
#>  os       Windows 10 x64 (build 19042)
#>  system   x86_64, mingw32
#>  ui       RTerm
#>  language (EN)
#>  collate  English_United States.1252
#>  ctype    English_United States.1252
#>  tz       America/New_York
#>  date     2022-02-22
#>  pandoc   2.11.4 @ C:/Program Files/RStudio/bin/pandoc/ (via rmarkdown)
#> 
#> - Packages 
-------------------------------------------------------------------
#>  ! package     * version date (UTC) lib source
#>    arrow       * 7.0.0   2022-02-10 [1] CRAN (R 4.0.5)
#>  P assertthat    0.2.1   2019-03-21 [?] CRAN (R 4.0.5)
#>  P backports     1.4.1   2021-12-13 [?] CRAN (R 4.0.5)
#>  P bit           4.0.4   2020-08-04 [?] CRAN (R 4.0.5)
#>  P bit64         4.0.5   2020-08-30 [?] CRAN (R 4.0.5)
#>  P cli           3.2.0   2022-02-14 [?] CRAN (R 4.0.5)
#>  P crayon        1.5.0   2022-02-14 [?] CRAN (R 4.0.5)
#>  P digest        0.6.29  2021-12-01 [?] CRAN (R 4.0.5)
#>  P ellipsis      0.3.2   2021-04-29 [?] CRAN (R 4.0.5)
#>  P evaluate      0.14    2019-05-28 [?] CRAN (R 4.0.5)
#>  P fansi         1.0.2   2022-01-14 [?] CRAN (R 4.0.5)
#>  P fastmap       1.1.0   2021-01-25 [?] CRAN (R 4.0.5)
#>  P fs            1.5.2   2021-12-08 [?] CRAN (R 4.0.5)
#>  P glue          1.6.1   2022-01-22 [?] CRAN (R 4.0.5)
#>  P highr         0.9     2021-04-16 [?] CRAN (R 4.0.5)
#>  P htmltools     0.5.2   2021-08-25 [?] CRAN (R 4.0.5)
#>  P knitr         1.37    2021-12-16 [?] CRAN (R 4.0.5)
#>  P lifecycle     1.0.1   2021-09-24 [?] CRAN (R 4.0.5)
#>  P magrittr      2.0.2   2022-01-26 [?] CRAN (R 4.0.5)
#>  P pillar        1.7.0   2022-02-01 [?] CRAN (R 4.0.5)
#>  P pkgconfig     2.0.3   2019-09-22 [?] CRAN (R 4.0.5)
#>  P purrr         0.3.4   2020-04-17 [?] CRAN (R 4.0.5)
#>    R.cache       0.15.0  2021-04-30 [2] CRAN (R 4.0.5)
#>    R.methodsS3   1.8.1   2020-08-26 [2] CRAN (R 4.0.3)
#>    R.oo          1.24.0  2020-08-26 [2] CRAN (R 4.0.3)
#>    R.utils       2.11.0  2021-09-26 [2] CRAN (R 4.0.5)
#>  P R6            2.5.1   2021-08-19 [?] CRAN (R 4.0.5)
#>  P reprex        2.0.1   2021-08-05 [?] CRAN (R 4.0.5)
#>  P rlang         1.0.1   2022-02-03 [?] CRAN (R 4.0.5)
#>  P rmarkdown     2.11    2021-09-14 [?] CRAN (R 4.0.5)
#>  P rstudioapi    0.13    2020-11-12 [?] CRAN (R 4.0.5)
#>  P sessioninfo   1.2.2   2021-12-06 [?] CRAN (R 4.0.5)
#>  P stringi       1.7.6   2021-11-29 [?] CRAN (R 4.0.5)
#>  P stringr       1.4.0   2019-02-10 [?] CRAN (R 4.0.5)
#>    styler        1.6.2   2021-09-23 [2] CRAN (R 4.0.5)
#>  P tibble        3.1.6   2021-11-07 [?] CRAN (R 4.0.5)
#>  P tidyselect    1.1.2   2022-02-21 [?] CRAN (R 4.0.5)
#>  P utf8          1.2.2   2021-07-24 [?] CRAN (R 4.0.5)
#>  P vctrs         0.3.8   2021-04-29 [?] CRAN (R 4.0.5)
#>  P withr         2.4.3   2021-11-30 [?] CRAN (R 4.0.5)
#>  P xfun          0.29    2021-12-14 [?] CRAN (R 4.0.5)
#>  P yaml          2.3.5   2022-02-21 [?] CRAN (R 4.0.5)
#> 
#>  [1] 
C:/Users/jalsal02/R/renv/library/arrow-nightly-d7265b80/R-4.0/x86_64-w64-mingw32
#>  [2] C:/Users/jalsal02/R/dev-library/4.0
#>  [3] C:/Program Files/R/R-4.0.5/library
#> 
#>  P -- Loaded and on-disk path mismatch.
#> 
#> 
------------------------------------------------------------------------------
```

</details>

> [R] Memory usage in R blows up
> ------------------------------
>
>                 Key: ARROW-15730
>                 URL: https://issues.apache.org/jira/browse/ARROW-15730
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: R
>            Reporter: Christian
>            Assignee: Will Jones
>            Priority: Major
>             Fix For: 6.0.1
>
>         Attachments: image-2022-02-19-09-05-32-278.png
>
>
> Hi,
> I'm trying to load a ~10gb arrow file into R (under Windows)
> _(The file is generated in the 6.0.1 arrow version under Linux)._
> For whatever reason the memory usage blows up to ~110-120gb (in a fresh and 
> empty R instance).
> The weird thing is that when deleting the object again and running a gc() the 
> memory usage goes down to 90gb only. The delta of ~20-30gb is what I would 
> have expected the dataframe to use up in memory (and that's also approx. what 
> was used - in total during the load - when running the old arrow version of 
> 0.15.1. And it is also what R shows me when just printing the object size.)
> The commands I'm running are simply:
> options(arrow.use_threads=FALSE);
> arrow::set_cpu_count(1); # need this - otherwise it freezes under windows
> arrow::read_arrow('file.arrow5')
> Is arrow reserving some resources in the background and not giving them up 
> again? Are there some settings I need to change for this?
> Is this something that is known and fixed in a newer version?
> *Note* that this doesn't happen in Linux. There all the resources are freed 
> up when calling the gc() function - not sure if it matters but there I also 
> don't need to set the cpu count to 1.
> Any help would be appreciated.



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