Quick way to crash APE: store a not so big array - out of memory

[Nicolas]

Hi,

I am really puzzled by this one. I have been looking at memory issues (leaks?) in my program.

Here is a simple routine to make APE crash pretty quickly.

g_user_info=[];

for (var user_id=1;user_id<=10000;user_id++){

    Ape.log("user_id:"+user_id);

    g_user_info[user_id]=[];

    for (var i=1;i<=7;i++){

       g_user_info[user_id][i]=[];

    }

    

    //Ape.log(mydump(g_user_info));

}

To reproduce the crash, simply put this at the top of your commands.js file and run APE.

On my dev machine, APE reaches user_id=9,000. On my prod machine, even less, only 6,800.

I am really puzzled as to why such a small array should make APE crash. 7,000 * 7 is not such a big number, right?

So two questions:

1) Can you reproduce the issue?

2) Have you got an explanation? Am I doing something wrong here?

Thanks for your precious help.

[Nicolas]

Actually, this can even be simplified. There is no need for several loops. This is enough to make APE crash quickly.

for (var user_id=1;user_id<=1000000;user_id++){

    g_user_info[user_id]=[];

}

BTW, replacing [] by {} does not help (actually just a little, crashes come 50% later)

I strongly suspect the way memory is allocated to be the issue. Does anyone know how APE handles arrays?

There seems to be a small maximum.

[peter.r...@verpeteren.nl]

hai

In this case, the memory allocation is handled by the spidermonkey
engine.
I guess that the runtime enforces this as a limit. See
./src//modules/libape-spidermonkey.c#L5484
rt = JS_NewRuntime(8L * 1024L * 1024L);


Peter

Nicolas schreef op 2014-12-04 16:03:

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[Nicolas]

Many thanks Peter. Very helpful.

I guess I have to recompile APE with bigger values.

Any idea why the limit is so low?

I figure a 100,000 array is very small and am very suprized noone else ever ran into this limitation.

Thanks again.

[Nicolas]

Bingo!!

I changed to:

     rt = JS_NewRuntime(8L*8L * 1024L * 1024L); 

and even:

     rt = JS_NewRuntime(8L*8L*8L * 1024L * 1024L); 

It worked.

I can now generate 64 more objects!

Many thanks!

I strongly suggest to put this last line as default in APE. I don't see why this would be a problem (and I can tell you the existing line has caused me weeks of time!).

Thoughts?

PS: many many thanks Peter and Anthony!