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

[hugovk]

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

Before

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

After

❯ ./python.exe -m json --json-lines input.jsonl
{
    "ingredients": [
        "frog",
        "water",
        "chocolate",
        "glucose"
    ]
}
{
    "ingredients": [
        "chocolate",
        "steel bolts"
    ]
}

• Issue: JSON CLI: I/O operation on closed file" when parsing JSON Lines file #132631

[zware]

This has significant memory implications for large .jsonl files. It might be better to instead move the finally clause either to the outer try or just after the with outfile block, but that does have implications for the infile == outfile case.

[hugovk]

Hmm, yeah, moving it gives a blank file when infile == outfile...

[hugovk]

Or we could load all the lines into a list. This uses more memory than before, but less than the tuple as we're only deserialising each line when consumed from the generator:

Suggested change

	objs = tuple(json.loads(line) for line in infile)
	lines = infile.readlines()
	objs = (json.loads(line) for line in lines)

I don't think it's worth adding much extra complexity for this CLI, as if someone needs to process extremely large .jsonl files they can write their own code to do exactly what they need.

[python-cla-bot]

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