Description

hugovk

opened on Apr 17, 2025

Issue body actions

Bug report

Bug description:

With any JSON Lines file, such as:

❯ cat input.jsonl
{"ingredients":["frog", "water", "chocolate", "glucose"]}
{"ingredients":["chocolate","steel bolts"]}

This works on Python 3.12:

❯ python3.12 --version
Python 3.12.10

❯ python3.12 -m json.tool --json-lines input.jsonl
{
    "ingredients": [
        "frog",
        "water",
        "chocolate",
        "glucose"
    ]
}
{
    "ingredients": [
        "chocolate",
        "steel bolts"
    ]
}

But not 3.13 or higher:

❯ python3.13 --version
Python 3.13.3

❯ python3.13 -m json.tool --json-lines input.jsonl
I/O operation on closed file.

❯ python3.14 --version
Python 3.14.0a7

❯ python3.14 -m json.tool --json-lines input.jsonl
I/O operation on closed file.

❯ ./python.exe --version --version
Python 3.14.0a7+ (heads/main:e42bda94411, Apr 17 2025, 14:59:38) [Clang 16.0.0 (clang-1600.0.26.6)]

❯ ./python.exe Lib/test/test_json/test_tool.py -h

❯ ./python.exe -m json.tool --json-lines input.jsonl
I/O operation on closed file.

CPython versions tested on:

3.13, 3.14, CPython main branch

Operating systems tested on:

macOS, Linux

Linked PRs

• gh-132631: Fix "I/O operation on closed file" when parsing JSON Lines file #132632
• gh-132631: Fix json.tool when using --json-lines and a file as input #138961
• [3.14] gh-132631: Fix "I/O operation on closed file" when parsing JSON Lines file (GH-132632) #148921
• [3.13] gh-132631: Fix "I/O operation on closed file" when parsing JSON Lines file (GH-132632) #148922

Activity

1. hugovk

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   3.13only security fixesonly security fixes

   3.14bugs and security fixesbugs and security fixes

   on Apr 17, 2025
2. hugovk

   marked json.tool error I/O operation on close file with --json-lines #138960 as a duplicate of this issue on Sep 16, 2025
3. nineteendo commented on Sep 16, 2025

   

   nineteendo

   on Sep 16, 2025 · Hidden as resolved

   show commentMore actions
4. hugovk

   added this to JSON issueson Sep 16, 2025
5. mpkocher commented on Sep 16, 2025

   

   mpkocher

   on Sep 16, 2025

   Contributor

   More actions

   There's also an issue with the "in place" functionality. This is captured in a unit test, but there's no mention of this requirement or functionality in the code.

   In place can overwrite the current file, but requires special attention.

   python -m json.tool example.json example.json

   For the in place functionality, it should probably write to a tmp file, then atomically overwrite the original file and delete the tmp file.

   The use case of in place and --json-lines is a bit odd (needs --no-indent), but it still should mechanically work and not error out.

   >> cat a.jline                                                
   {"alpha": 123,                     "beta": 122345}
   {"alpha": 124,       "beta": 456}

   From a file, using --no-indent can cleanup a file.

   >> python  -m json.tool --no-indent --json-lines a.jline 
   {"alpha": 123, "beta": 122345}
   {"alpha": 124, "beta": 456}

   In place will break and overwrite the original file and leave an empty file, effectively deleting(!) the original file.

   >> cat a.jline       
   {"alpha": 123,                     "beta": 122345}
   {"alpha": 124,       "beta": 456}
   >> python -m json.tool --json-lines --no-indent a.jline a.jline
   I/O operation on closed file.
   >> cat a.jline 
   >>
6. hugovk

   added 3 commits that reference this issue on Apr 23, 2026

   gh-132631: Fix "I/O operation on closed file" when parsing JSON Lines…

   42d645a

   [3.14] gh-132631: Fix "I/O operation on closed file" when parsing JSO…

   31ba91a

   [3.13] gh-132631: Fix "I/O operation on closed file" when parsing JSO…

   e4ae72a
7. hugovk

   closed this as completedon Apr 23, 2026
8. github-project-automation

   moved this to Done in JSON issueson Apr 23, 2026
9. ljfp

   added a commit that references this issue on Apr 25, 2026

   pythongh-132631: Fix "I/O operation on closed file" when parsing JSON…

   a17f00e

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