Replace pmap gem with pure-Ruby thread pool#14
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git_report's only dependency was the pmap gem, used for parallel `map`/`each` over authors, emails, and file slices. Replace it with a small in-tree helper (Git::Parallel) built on the standard library, so the tool now runs on stock Ruby with no gems to install. - Add lib/git/parallel.rb: a bounded worker pool (MAX_THREADS = 64, matching pmap's historical default) providing pmap/peach. The cap is essential -- one thread per author would spawn thousands of git subprocesses on large repositories. Workers drain a pre-filled queue and exit when empty; Thread#value propagates the first worker exception to the caller. - author.rb: accumulate +LOC/-LOC on the main thread after the parallel blocks return, fixing a latent cross-thread `+=` race. - bin/git_report: drop the gem-vendoring/first-run install machinery that existed solely to install pmap; the launcher is now a few lines. - Gemfile: remove `gem 'pmap'`; keep it dependency-free. - Update README and smoke-test comments to reflect zero dependencies. Verified: smoke test passes on Ruby 3.4, runs on stock macOS Ruby 2.6 with no gems, RuboCop clean, and a 5000-item stress test confirms concurrency never exceeds the 64-thread cap.
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Summary
git_report's only dependency was thepmapgem, used for parallelmap/eachover authors, emails, and file slices. This replaces it with a small in-tree helper,Git::Parallel, built entirely on the Ruby standard library. The tool now runs on stock Ruby (including the macOS system Ruby) with nothing to install.What changed
lib/git/parallel.rb(new) — a bounded worker pool providingpmap/peach.MAX_THREADS = 64matches pmap 1.1.1's historical default, so throughput on large repos is unchanged. The cap is essential: a naive one-thread-per-element version would spawn thousands of concurrentgitsubprocesses on a large repo (a fork bomb). Workers drain a pre-filled queue and exit when empty;Thread#valuepropagates the first worker exception to the caller.lib/git/author.rb—+LOC/-LOCnow accumulate on the main thread after the parallel blocks return, fixing a latent cross-thread+=race that existed under the oldpmapusage too.bin/git_report— removed the gem-vendoring / first-rungem installmachinery that existed solely to install pmap. The launcher is now a few lines.Gemfile— removedgem 'pmap'; the project is now dependency-free.Verification
2 runs, 12 assertions, 0 failures)7 files, no offenses)