On 5/22/2013 1:32 PM, Geoff Leyland wrote:
On 23/05/2013, at 7:43 AM, madigest i <madigest@xxxxxxxxxxxxx> wrote:Hello. I have had strange performance problems with many of my different Lua programs that handle big strings. I finally made a small test program to demonstrate the problem. Here are the results in OSX: LuaJIT 2.1.0-alpha: 46 seconds LuaJIT 2.0.1: 39 seconds Lua 5.1: 22 secondsLuaJIT 2 doesn't compile string concatenation, and LuaJIT 2.1 doesn't compile the gmatch. I realise this is a test case, not your real code, but why isn't your inner loop like: local codeout = {} local timeUsed = os.time() for line in code:gmatch("[^\r\n]+") do codeout[#codeout+1] = line.."\n" end codeout = table.concat(codeout, "") timeUsed = os.time() - timeUsed That takes 0s on all versions. (Use os.clock in preference to os.time, it has better resolution)
Yup. Increasing the linecount numbers, and I'm getting 0.3sec for lua, 0.2sec for luajit (-joff or not)
-- luajit_speed_test.lua
--local codeout = ""
local codeout = {}
local linecount = 20000
local strlen = 100
local line = string.rep("a", strlen).."\n"
local code = string.rep(line, 200000)
local i = 0
local timeUsed = os.clock()
for line in code:gmatch("[^\r\n]+") do
i = i + 1
--for i=1,linecount do
if i%10000 == 0 or i == 1 then
print(" ... line: "..i.." / "..linecount)
end
--codeout = codeout..line.."\n"
codeout[#codeout+1] = line
end
codeout = table.concat(codeout, "\n")
timeUsed = os.clock() - timeUsed
if jit then
print(jit.version..": "..timeUsed.." seconds")
else
print(_VERSION..": "..timeUsed.." seconds")
end
print(" -- luajit_speed_test.lua end -- ")
print()
