wc: wc -c does not optimize stdin as input by metadata
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U - wc
- Dominant language
- Rust
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Description
We have splice for pipe at input:
$ truncate -s 32GB huge
$ time cat huge| gnu58d88d243/wc -c
32000000000
real 0m2.012s
user 0m0.128s
sys 0m3.873s
$ time cat huge| wc -c
32000000000
real 0m0.388s
user 0m0.042s
sys 0m0.650s
that's fine. But uutils does not optimize stdin by metadata:
$ time wc -c <huge
32000000000
real 0m1.662s
user 0m0.040s
sys 0m1.612s
$ time gnu58d88d243/wc -c < huge
32000000000
real 0m0.004s
user 0m0.002s
sys 0m0.002s
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the wc -c command path for stdin redirected from a regular file and reproduce the huge benchmark shown in the issue. Trace how stdin is read and how file metadata is used; done means the byte count remains correct while matching the metadata-based performance of GNU wc for this case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- cli, performance
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 55/100