this post was submitted on 30 Mar 2026
10 points (100.0% liked)

Programming

26370 readers
173 users here now

Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!

Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.

Hope you enjoy the instance!

Rules

Rules

  • Follow the programming.dev instance rules
  • Keep content related to programming in some way
  • If you're posting long videos try to add in some form of tldr for those who don't want to watch videos

Wormhole

Follow the wormhole through a path of communities !webdev@programming.dev

founded 2 years ago
MODERATORS
snowe@programming.dev
Ategon@programming.dev
UlrikHD@programming.dev
bugsmith@programming.dev
Spyro@programming.dev
10
How would you design parallel grep for huge JSONL files? (lemmy.world)
submitted 6 days ago by dhruv3006@lemmy.world to c/programming@programming.dev
21 comments fedilink hide all child comments
 

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.

you are viewing a single comment's thread
view the rest of the comments
[–] Lysergid@lemmy.ml 3 points 6 days ago

How large is very large? Would it be something that jq can’t do? Is it purely string search or JSON-tree search?

Generally you would want to get file size, split it into ranges which can be read as valid UTF-8. Feed each range into reader thread. Can be inefficient for HDDs because each thread will try to access random location on disk forcing needle to jump back and forth. Also you’ll need reread ranges at split point with some positive and negative offset in case desired content got split. Things are getting much more complicated if you want JSON-tree grep. Branches may get split from parent nodes across multiple ranges.