cp command implementation and benchmark in python, go, lua

I was wondering how much will be the speed difference between cp command, rsync and implementation in python, go, lua and so wrote this code.

Background

  1. python has two versions one with gevent and without gevent. Both the version uses shutil for copying files and directory tree.
  2. go uses https://github.com/opesun/copyrecur for copying recursively.
  3. lua uses lfs - LuaFileSystem module. lfs has support for creating directory but not for files, in order to copy the files low level file opening and writing to file technique is used.
  4. rsync --progress -ah -R was also added to the test.

Code

Directory chosen for the test has 28 repos which are basically python projects, go repos with git version control. Total size of the directory /Users/kracekumarramaraju/code is 300M(du -sh /Users/kracekumarramaraju/code) and destination is external disk which supports USB3.0.

Python without gevent

import sys
import shutil


def cp(source, dest):    
    shutil.copytree(source, dest)


if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Help")
        print("python cp.py source dest is the format")
        sys.exit(1)
    cp(sys.argv[1], sys.argv[2])

Python with gevent support

import sys
import os
import shutil
import gevent


def cp(source, dest):
    shutil.copytree(source, dest)


def cpfile(source, dest):
    shutil.copy2(source, dest)


if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Help")
        print("python cp.py source dest is the format")
        os.exit(1)
    source, dest = sys.argv[1], sys.argv[2]
    os.mkdir(dest)
    tasks = []
    for name in os.listdir(source):
        source_path, dest_path = os.path.join(source, name), os.path.join(dest, name)
        if os.path.isdir(source_path):
            tasks.append(gevent.spawn(cp, source_path, dest_path))
        else:
            tasks.append(gevent.spawn(cpfile, source_path, dest_path))
    gevent.joinall(tasks)

go

package main

import (
    "fmt"
    "github.com/opesun/copyrecur"
    "log"
    "os"
)

func cp(source, dest string) {
    err := copyrecur.CopyDir(source, dest)
    if err != nil {
        log.Fatal(err)
    } else {
        log.Print("Files copied.")
    }
}

func main() {
    if len(os.Args) != 3 {
        fmt.Println("Syntax: go run cp.go source destination")
        os.Exit(1)
    }
    cp(os.Args[1], os.Args[2])
    fmt.Println("cp.go completed")
}

lua

require "lfs"


function cp(source, dest)
    -- body
    for filename in lfs.dir(source) do
        if filename ~= '.' and filename ~= '..' then
            local source_path = source .. '/' .. filename
            local attr = lfs.attributes(source_path)
            --print(attr.mode, path)
            if type(attr) == "table" and attr.mode == "directory" then 
                local dest_path = dest .. "/" .. filename
                lfs.mkdir(dest_path)
                cp(source_path, dest_path)
            else
                local f = io.open(source_path, "rb")
                local content = f:read("*all")
                f:close()
                local w = io.open(dest .. "/" .. filename, "wb")
                w:write(content)
                w:close() 
            end
        end
    end
end

if #arg == 2 then
    cp(arg[1], arg[2])
else
    print("Syntax:")
    print("lua lua.go source dest")
end

rsync --progress -ah -R.
Plain cp command.

Tests

Shell script to run the tests.

echo "source directory size"
du -sh /Users/kracekumarramaraju/code
echo "cp.py - Python without gevent"
time python cp.py /Users/kracekumarramaraju/code /Volumes/My\ Passport/test/1
du -sh /Volumes/My\ Passport/test/1
echo "cp-gevent.py - Python with gevent"
time python cp-gevent.py /Users/kracekumarramaraju/code /Volumes/My\ Passport/test/2
du -sh /Volumes/My\ Passport/test/2
echo "alias cp='rsync --progress -ah' - Rsync"
time cp -R /Users/kracekumarramaraju/code /Volumes/My\ Passport/test/3
du -sh /Volumes/My\ Passport/test/3
echo "Plain cp command"
time /bin/cp -R /Users/kracekumarramaraju/code /Volumes/My\ Passport/test/4
du -sh /Volumes/My\ Passport/test/4
echo "cp.go - cp in Go lang"
time go run cp.go /Users/kracekumarramaraju/code /Volumes/My\ Passport/test/5
du -sh /Volumes/My\ Passport/test/5
echo "cp.lua - cp in lua"
time lua cp.lua /Users/kracekumarramaraju/code /Volumes/My\ Passport/test/6
du -sh /Volumes/My\ Passport/test/6

Results

➜  cp-tests  ./test.sh
source directory size
300M    /Users/kracekumarramaraju/code
cp.py - Python without gevent

real    1m23.354s
user    0m1.818s
sys 0m5.032s
302M    /Volumes/My Passport/test/1
cp-gevent.py - Python with gevent

real    1m24.212s
user    0m1.772s
sys 0m4.748s
302M    /Volumes/My Passport/test/2
alias cp='rsync --progress -ah' - Rsync

real    1m21.145s
user    0m0.230s
sys 0m5.172s
302M    /Volumes/My Passport/test/3
Plain cp command

real    1m24.065s
user    0m0.232s
sys 0m5.174s
302M    /Volumes/My Passport/test/4
cp.go - cp in Go lang
2013/06/23 21:04:38 Files copied.
cp.go completed

real    1m27.786s
user    0m1.106s
sys 0m3.369s
302M    /Volumes/My Passport/test/5
cp.lua - cp in lua

real    1m19.340s
user    0m1.905s
sys 0m3.893s
302M    /Volumes/My Passport/test/6

Conclusion

  1. Surprisingly lua was fastest with 1m19.340s and next one was rsync with 1m21.145s.
  2. Slowest one was go with 1m27.786s, I expected it to be faster than python gevent. Probably extra time was due to compiling go code.
  3. Python non gevent version took 1m23.354s and gevent version took 1m24.212s, gevent version spent less time in user and system space.
  4. cp command took 1m24.065s, which was second slowest.
  5. Since the test was basically I/O there ins’t much difference in speed of all versions.

Further work

  1. Benchmark 1GB single file transfer using lua and rsync.
  2. Add all features of cp command to any one of the implementation and bench mark.

See also

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