How to free memory after required modules

[espruino-discuss]

Posted at 2014-03-27 by JumJum

Is there a way to free memory for unused parts, loaded with require ?
This could help for:

• handle functions during startup only
• create objects and remove them after use
• dynamically load and unload fonts for display
• ....

[gfwilliams]

Posted at 2014-03-27 by @gfwilliams

Sure, just use Modules.removeAllCached. There's another function that'll just remove a specific module too.

[espruino-discuss]

Posted at 2014-03-27 by JumJum

There may be a misunderstanding. I want to free memory.
Starting with this:

var g = require("ILI9341").connect(SPI2,C6,C7,C8,function(){g.clear();});

Process.memory() returns usage 329
Dump shows var g = { ..... digitalWrite(C6,1....
Result is as expected

g = "";

Process.memory() returns usage 331
dump shows var g = ""; digitalWrite(C6,1.....
I expected less memory usage

Modules.removeAllCached(); 

Process.memory() returns usage 330
dump shows var g = ""; digitalWrite(C6,1.....
I expected less memory usage
Tried to do this:

var b = "ILI9341";
g = require(b).connect(....

returns unable to read file no path
Process.memory() still returns usage 332
There is no object, no module, so how do I get rid of memory consumption ?

[gfwilliams]

Posted at 2014-03-27 by @gfwilliams

No misunderstanding - I think there might be a bug in Espruino - I'll look into it.

If you try a different module it works as I suggested:

>process.memory().usage
=17
>g=require("KeyPad")
={ ... }
>process.memory().usage
=61
>g=""
=""
>process.memory().usage
=62
>Modules.removeAllCached()
=undefined
>process.memory().usage
=19

[espruino-discuss]

Posted at 2014-03-28 by JumJum

Great, just tested nightly build and it works fine.

What I'm doing now is to use something like this:

1. copy my modules to sdcard in folder node_modules
2. use require by variable not by string to avoid loading from WebIDE
3. clear modules after running my init procedure

var b,n;
n = "myModule";
b = require(n).connect(......
// do a lot of functions
b = ""; //to delete the object created during require
Modules.removeCached(n);
// do whatever is used after initialization

Next test will be to split an application into modules which are loaded and unloaded by a main application.

[gfwilliams]

Posted at 2014-03-28 by @gfwilliams

Great! So are you actually running out of space, or is this 'just in case'?

By the way, you can also do eval(require('fs').readFile("...")) which might be slightly easier if you're loading specific bits of code.

Espruino is designed so that it can 'page' variables and code out to flash - potentially giving it massively more available memory. It could be a fun project for someone :)

[espruino-discuss]

Posted at 2014-03-28 by JumJum

I ran out of memory by creating an extended module for ILI9341 and adding simple charts, so called "PicoChart". SPI.send ran out of memory during processing.
After restructering etc. there have been about 300 blocks left. Minimizing and some other changes brought it down to about 1000 blocks left.