# Closing files when using CSV.Rows
**URL:** https://discourse.julialang.org/t/closing-files-when-using-csv-rows/29169
**Category:** General Usage
**Tags:** question, csv
**Created:** [September 25, 2019, 3:58pm UTC](https://discourse.julialang.org/t/closing-files-when-using-csv-rows/29169 "2019-09-25T15:58:09Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)
#### Post date: [September 25, 2019, 3:58pm UTC](https://discourse.julialang.org/t/closing-files-when-using-csv-rows/29169/1 "2019-09-25T15:58:09Z")
I’m using `CSV.Rows` to iterate through a very large CSV file. In base Julia, files that are opened with `open` should be closed with `close` (or you can use the `do` syntax instead). However, after perusing the CSV.jl docs, there doesn’t appear to be a `close` method for file iterators created with `CSV.Rows`. How does CSV.jl ensure that files are closed when they’re done being used? Does it just rely on the files being closed when the `CSV.Rows` object gets garbage collected?
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### Author:  [@nalimilan](https://discourse.julialang.org/u/nalimilan)
#### Post date: [September 27, 2019, 9:14pm UTC](https://discourse.julialang.org/t/closing-files-when-using-csv-rows/29169/2 "2019-09-27T21:14:27Z")
Cc: @quinnj
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### Author:  [@quinnj](https://discourse.julialang.org/u/quinnj)
#### Post date: [October 3, 2019, 1:59am UTC](https://discourse.julialang.org/t/closing-files-when-using-csv-rows/29169/3 "2019-10-03T01:59:01Z")
Sorry for the slow response here, and thanks @nalimilan for the ping. There’s a few different paths here depending on how you use `CSV.Rows`:
- If you pass the file as a string, like `CSV.Rows("filename.csv")`, then CSV.jl will mmap the file by default, which indeed then relies on the `CSV.Rows` object getting garbage collected to unmmap the file buffer
- You can also pass in your own opened file, like `io = open("filename.csv"); CSV.Rows(io)`, which currently will “slurp” the entire file into a mmapped buffer to be used while reading rows. So you would need to close the `io` yourself afterwards
Hopefully that helps!
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### Author:  [@Davide\_DelVento](https://discourse.julialang.org/u/Davide_DelVento)
#### Post date: [September 9, 2024, 11:37pm UTC](https://discourse.julialang.org/t/closing-files-when-using-csv-rows/29169/4 "2024-09-09T23:37:20Z")
This applies also to `CSV.write`, correct?
I thought those would be immediately closed (since they are writing a full table, not a single row), but looking at its source code it does not appear to be so.
Reason for asking: debugging a problem and understanding if a file is closed immediately after the function call, or rather later when the interpreter has time to run the garbage collector would help tremendously.
Thanks!