Re: Tables with Longs as Keys eating RAM

[Max De Marzi <maxdemarzi@...>]

Turns out it was neither. It was the actual JSON encoder I was using to return results. You hit the nail on the head. Problem solved.

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From: Thijs Schreijer <thijs@thijsschreijer.nl>
Sent: Wednesday, October 5, 2022 12:43 PM
To: Lua mailing list <lua-l@lists.lua.org>
Subject: Re: Tables with Longs as Keys eating RAM

 

On 30 Sep 2022, at 20:35, Max De Marzi <maxdemarzi@hotmail.com> wrote:

The code below runs just fine on both of these online Lua websites.

https://www.lua.org/cgi-bin/demo 
https://luajit.me/

local tab = {} 

tab[938388893] = "hi" 

tab[987383332] = "Hello"

for k,v in pairs(tab) do

 print(k) 

print (v) 

end

But when I try it using the Sol2 library (embedded in C++) it eats all my memory. 

It seems to create a giant table with the array part full of mostly empty values and just those two strings in their corresponding array slots.

Is it a Sol2 issue or a C Lua binding issue? Anybody know?

I’d say probably Sol. It’s a matter of modelling the data. I’ve seen the same issue with JSON encoders that check a table for integer-only keys, and then assume the thing is to be encoded as an array. This obviously ends up as one massive JSON blob.

I don’t know Sol, but maybe add a dummy-key (non-integer) to the table, to force it to not encode as an array?

Thijs