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How would you design parallel grep for huge JSONL files? (lemmy.world)
submitted 7 months ago by to c/programming@programming.dev
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I need to scan very large JSONL files efficiently and am considering a parallel grep-style approach over line-delimited text.

Would love to hear how you would design it.

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[–] 4 points 7 months ago (2 children)

The question is, what will be your limiting factor: CPU or disk I/O? Parallel processing doesn't do much good if the workers have to wait on the disk to deliver more data. I'd start with an async architecture, where the program can do its processing while it is waiting on more data.

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  • [–] 4 points 7 months ago (1 child)

    One additinal trick is to compress your files before writing them to disk, using some kind of fast lightweight compression like parallel gzip (pigz command) or lzop. When parsing them, you will have smaller disk reads but higher CPU usage, which will give speed advantage if you have server-class CPU with lots of cache.

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