delta issue #824 reproduction

delta-repro-824

#!/usr/bin/env bash

# See https://vaneyckt.io/posts/safer_bash_scripts_with_set_euxo_pipefail/
set -o errexit -o errtrace -o nounset -o pipefail

build_oci_img () {
  docker build "$@" - <<'EOF'
  FROM archlinux
  RUN pacman -Sy > /dev/null
  RUN pacman -S --noconfirm --needed coreutils curl gcc bc git > /dev/null
  ENV CARGO_HOME=/usr/local
  RUN curl -fsSL 'https://sh.rustup.rs' | sh -s -- -y --profile minimal
  RUN /usr/local/bin/cargo install --version 0.10.2 git-delta && cp /usr/local/bin/delta /usr/local/bin/delta-0.10.2
  RUN /usr/local/bin/cargo install --version 0.11.0 git-delta && cp /usr/local/bin/delta /usr/local/bin/delta-0.11.0
  RUN /usr/local/bin/cargo install --version 0.11.2 git-delta && cp /usr/local/bin/delta /usr/local/bin/delta-0.11.2
  WORKDIR /repo
EOF
}

main() {
  build_oci_img
  docker run --rm -i "$(build_oci_img -q)" bash <<'EOF'
  benchmark-command() {
    local num_runs="${1:-100}"
    shift
    local before
    before=$(($(date +%s%N) / 1000000))
    printf 'Running command "%s" %d times\n' "$*" "${num_runs}"
    for _ in $(seq 1 "${num_runs}"); do
      eval -- "$@" > /dev/null
    done
    local after
    after=$(($(date +%s%N) / 1000000))
    local per_run
    per_run=$(bc < <(printf 'scale=2; %d/%d\n' $((after - before)) "${num_runs}"))
    echo "${per_run} ms per run ($((after - before)) ms total)"
  }

  benchmark-delta-versions() {
    for v in 0.10.2 0.11.0 0.11.2; do
      echo "Benchmarking version: $v"
      benchmark-command 10 "git diff --no-index a b | delta-${v} >| delta-${v}-result"
    done
  }

  main() {
    echo aaa > a
    echo aab > b
    git diff --no-index a b | delta
    benchmark-delta-versions
    echo "Spinning up 5000 processes"
    for i in {1..5000}; do
      nohup sleep 30 & &> /dev/null
    done
    echo "Process counts:"
    ps --no-headers -e -o fname | sort | uniq -c
    benchmark-delta-versions
  }

  main
EOF
}

main