I sometimes run into problems removing files from R on Windows due to file locks. Most recently I have had a problem doing this with the arrow package (see reprex below). Are there any tips for doing this? More concretely is there any way to run the finalizer for an object (thus removing the lock it has) without calling gc() which is not recommended in a package?
library(arrow)
#>
#> Attaching package: 'arrow'
#> The following object is masked from 'package:utils':
#>
#> timestamp
# create a FileSystemDataset object
filename <- tempfile(fileext = ".feather")
write_dataset(cars, filename, format = "feather")
ds <- open_dataset(filename, format = "feather")
ds
#> FileSystemDataset with 1 Feather file
#> speed: double
#> dist: double
#>
#> See $metadata for additional Schema metadata
# process the file in batches
scanner <- ScannerBuilder$create(ds)$BatchSize(batch_size = 4)$Finish()
reader <- scanner$ToRecordBatchReader()
batch_num <- 1
while(!is.null(batch <- reader$read_next_batch())) {
print(paste("Reading batch", batch_num, "with", nrow(batch), "rows"))
batch_num <- batch_num + 1
}
#> [1] "Reading batch 1 with 4 rows"
#> [1] "Reading batch 2 with 4 rows"
#> [1] "Reading batch 3 with 4 rows"
#> [1] "Reading batch 4 with 4 rows"
#> [1] "Reading batch 5 with 4 rows"
#> [1] "Reading batch 6 with 4 rows"
#> [1] "Reading batch 7 with 4 rows"
#> [1] "Reading batch 8 with 4 rows"
#> [1] "Reading batch 9 with 4 rows"
#> [1] "Reading batch 10 with 4 rows"
#> [1] "Reading batch 11 with 4 rows"
#> [1] "Reading batch 12 with 4 rows"
#> [1] "Reading batch 13 with 2 rows"
rm(reader)
rm(scanner)
rm(ds)
# remove the file
rc <- unlink(filename)
if(rc == 1) print("removal of file failed")
#> [1] "removal of file failed"
file.exists(filename)
#> [1] TRUE
# call gc()
gc()
#> used (Mb) gc trigger (Mb) max used (Mb)
#> Ncells 1107045 59.2 2378167 127.1 1234188 66.0
#> Vcells 1924043 14.7 8388608 64.0 3178079 24.3
# remove the file
rc <- unlink(filename)
if(rc == 1) print("removal of file failed")
#> [1] "removal of file failed"
file.exists(filename)
#> [1] TRUE
Created on 2022-10-18 by the reprex package (v2.0.1)
Session info
sessioninfo::session_info()
#> - Session info ---------------------------------------------------------------
#> setting value
#> version R version 4.0.5 (2021-03-31)
#> os Windows 10 x64
#> system x86_64, mingw32
#> ui RTerm
#> language (EN)
#> collate English_United States.1252
#> ctype English_United States.1252
#> tz America/New_York
#> date 2022-10-18
#>
#> - Packages -------------------------------------------------------------------
#> package * version date lib source
#> arrow * 9.0.0.2 2022-10-02 [1] CRAN (R 4.0.5)
#> assertthat 0.2.1 2019-03-21 [1] CRAN (R 4.0.5)
#> backports 1.4.0 2021-11-23 [1] CRAN (R 4.0.5)
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#> bit64 4.0.5 2020-08-30 [1] CRAN (R 4.0.5)
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#> rlang 1.0.2 2022-03-04 [1] CRAN (R 4.0.5)
#> rmarkdown 2.10 2021-08-06 [1] CRAN (R 4.0.5)
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#> sessioninfo 1.1.1 2018-11-05 [1] CRAN (R 4.0.5)
#> stringi 1.7.5 2021-10-04 [1] CRAN (R 4.0.5)
#> stringr 1.4.0 2019-02-10 [1] CRAN (R 4.0.5)
#> styler 1.5.1 2021-07-13 [1] CRAN (R 4.0.5)
#> tibble 3.1.2 2021-05-16 [1] CRAN (R 4.0.5)
#> tidyselect 1.1.2 2022-02-21 [1] CRAN (R 4.0.5)
#> tzdb 0.2.0 2021-10-27 [1] CRAN (R 4.0.5)
#> utf8 1.2.1 2021-03-12 [1] CRAN (R 4.0.5)
#> vctrs 0.3.8 2021-04-29 [1] CRAN (R 4.0.5)
#> withr 2.5.0 2022-03-03 [1] CRAN (R 4.0.5)
#> xfun 0.25 2021-08-06 [1] CRAN (R 4.0.5)
#> yaml 2.2.1 2020-02-01 [1] CRAN (R 4.0.5)
#>
#> [1] C:/Users/adam.DESKTOP-D3KQQA1/Documents/R/win-library/4.0
#> [2] C:/Program Files/R/R-4.0.5/library