Looks like patmch Lua implementation needs some collectgarbage() calls.

[agladysh]

Something along these lines:

-- These aliases would help plain Lua.
local io_lines = io.lines
local print = print -- Consider removing IO from all benchmarks, BTW.
local collectgarbage = collectgarbage

local pattern = (...)

local counter = 0
for l in io_lines() do
  if l:find(pattern) then print(l) end

  counter = counter + 1
  if counter % 1000 == 0 then -- Play with this value
    collectgarbage("step")
    counter = 0
  end   
end

I'll submit a pull request if you'd do #14.

[attractivechaos]

Using collectgarbage() makes no difference at all. Honestly, I think local print = print is over-optimization. That is not the way most Lua programmers write Lua. Also, I/O is not necessarily bad as long as it is not the bottleneck. It is not in this case and in the dictionary benchmark, in theory. (I will come to issue #13 later about this topic)

[agladysh]

Hmm, that is interesting. No difference — even for plain Lua?

[attractivechaos]

LuaJIT only. Haven't tried Lua.

[agladysh]

Well, local aliases are an optimization for plain Lua, as I stated in the comment.

[attractivechaos]

For plain Lua, slower with collectgarbage. EDIT: at least not faster.

[agladysh]

That is not the way most Lua programmers write Lua.

"Most" is arguable. We have about 600KLOC written in this style.

Note that the performance is not the only reason. If you do not do aliasing, your code wouldn't work in the sandbox with a custom global environment.

Couple of links from three seconds of googling:

• http://developer.coronalabs.com/content/performance-and-optimization#Use_locals_i.e._avoid_global_variables
• http://www.wowwiki.com/UI_best_practices
• http://www.lua.org/gems/sample.pdf
• http://www.luafaq.org/#T1.37

[agladysh]

For plain Lua, slower with collectgarbage. EDIT: at least not faster.

OK, this means that I misinterpreted that 999. See #18.

[attractivechaos]

Ok. I buy your argument. But anyway, no improvement to speed.

[agladysh]

Ok. I buy your argument. But anyway, no improvement to speed.

Even not for plain Lua? Strange. Thanks for trying, anyway.