The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Tuesday, November 10, 2009

Perhaps an 80M script isn't that excessive …

Okay, I played around a bit with the Lua code from last night. Here, again, is the six minute run:

[spc]lucy:/tmp/lua>time lua -i show.lua
Lua 5.1.4  Copyright (C) 1994-2008, PUC-Rio
> dofile("default.lua")
> os.exit()

real    5m49.052s
user    5m43.279s
sys     0m0.577s

show.lua is some code to display a given table, and it's only being used here to see if the code actually built the huge table up correctly.

Okay, six minutes. I'm not sure what prompted me to do the following, but I did it anyway:

[spc]lucy:/tmp/lua>time lua -i default.lua
Lua 5.1.4  Copyright (C) 1994-2008, PUC-Rio
> dofile("show.lua")
> os.exit()

real    0m12.354s
user    0m6.293s
sys     0m0.413s

Oooohkaaaaay … what happend here? To make matters more interesting, it's repeatable. I load show.lua (at 1,101 bytes) first, and it takes six minutes. Load default.lua (the 80MB file) and it takes 12 seconds. And if I do it this way:

[spc]lucy:/tmp/lua>time lua
Lua 5.1.4  Copyright (C) 1994-2008, PUC-Rio
> dofile("show.lua")
> dofile("default.lua")
> os.exit()

real    0m16.130s
user    0m6.311s
sys     0m0.365s

and it takes 16 seconds (only because it took me an additional four seconds to type the extra line of code).

Very weird.

Update Wednesday, February 3rd, 2010

It was a bug in Lua that has since been fixed.

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