echo: Reduce memory allocation

[AnuthaDev]

Replaced the vector allocation in filter_flags with direct iterator usage for reduced memory overhead.

Added new tests to cover edge cases encountered during previous implementation attempts.

Memory Usage Analysis:

Using /usr/bin/time (Linux)

1. Create a test input file: printf "00 %.0s" {1..100000} > args.txt
2. Run the binary:

 /usr/bin/time -v ./target/release/coreutils echo $(cat args.txt)

Results:

1. main: Maximum resident set size (kbytes): 19364

2. This PR: Maximum resident set size (kbytes): 12280

3. System echo: Maximum resident set size (kbytes): 2544

Using dhat-rs:

main:

./target/release/coreutils echo $(cat args.txt) > /dev/null

dhat: Total:     10,065,406 bytes in 200,206 blocks
dhat: At t-gmax: 7,647,027 bytes in 200,135 blocks
dhat: At t-end:  2,648,051 bytes in 100,134 blocks

This PR:

./target/release/coreutils echo $(cat args.txt) > /dev/null

dhat: Total:     5,264,197 bytes in 200,188 blocks
dhat: At t-gmax: 5,000,140 bytes in 100,005 blocks
dhat: At t-end:  2,648,047 bytes in 100,134 blocks

[ChrisDryden]

This is great work, I'd love to see if we had a way to track these changes over time. What was the main method you used for determining the memory usage, did you set up a benchmark?

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/shuf/shuf-reservoir is no longer failing!
Congrats! The gnu test tests/sort/sort-stale-thread-mem is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/shuf/shuf-reservoir is no longer failing!
Congrats! The gnu test tests/sort/sort-stale-thread-mem is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/shuf/shuf-reservoir is no longer failing!
Congrats! The gnu test tests/sort/sort-stale-thread-mem is no longer failing!

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing AnuthaDev:echo-alloc (db22117) with main (b804ca4)}

Summary

✅ 140 untouched benchmarks
⏩ 37 skipped benchmarks¹

Footnotes

1. 37 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[AnuthaDev]

Hey @ChrisDryden , for benchmarking I used /usr/bin/time in the beginning and later shifted to dhat.

I believe the dhat crate can be used in a CI pipeline to keep track of memory allocation changes over time.

[sylvestre]

seems unrelated to this pr ?!

[AnuthaDev]

This PR removes the length check from args in case of --help and --version and instead uses other logic to infer the length

These test cases serve as additional confirmation that the changes did not regress any behaviour.

[sylvestre]

it makes our life harder as reviewers
and given your current stack of patches:

we will have to squash it and it won't be only for memory usage anymore

so, yeah, splitting it or writing a nice stack of patches would be appreciated

[AnuthaDev]

Improved the patchset. Please let me know if any further improvements are required.

[sylvestre]

same, unrelated

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)

[AnuthaDev]

The CI failure logs seem to indicate its unrelated to the PR changes? It was working with the same code earlier...