sometimes match or gmatch are very slow under luajit (compared to raw lua)
- From: Ronan Collobert <ronan@xxxxxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Tue, 18 Sep 2012 14:00:55 +0200
Hi,
Under certain conditions that I am unable to determine, string.match or
string.gmatch are very slow on luajit, compared to raw lua (x10 or even x25
slower).
It seems not to be related to the match pattern: a simple gmatch('(.-)\n') to
get the number of lines of the file might already a concern.
I try to generate random files where this would happen, with no success: I
really can't find the "trigger" which makes the thing (match or gmatch) slow.
In attachment I provide a small example (tar-gz archive) where I do get this
slowdown, both on my Mac OS 10.6 (i7 2.8Ghz) or on my Ubuntu 10.04.4 LTS (i7
3.07 Ghz):
time luajit test.lua
real 0m1.107s
user 0m1.100s
sys 0m0.000s
time lua test.lua
real 0m0.151s
user 0m0.130s
sys 0m0.020s
I am using the last luaJIT from the luajit-2.0 git master branch, as well as
lua 5.1.4.
Any idea?
I noticed someone posted a somewhat related problem previously:
//www.freelists.org/post/luajit/Luajit-string-split-much-much-slower-that-Lua-string-split
Cheers
Ronan
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