Objective-C plugin crashes with initialization of large array - objective-c

Question

I am working on a plugin in objective-C which I am running in Osirix. At some point in the plugin I initialize two large arrays (which are meant to accept a 512x512 image which is later fed into a CoreML model). The original plugin used a coreml model which accepted 200x200 sized images, the var IMG_SQSIZE was set as 200^2 and everything worked fine. Now I have increased IMG_SQSIZE to 512^2 but this crashes the plugin. If I the array initialization and everything after there is no crash, if I keep this line but remove everything after the crash persists...so I've concluded that this is causing the problem. I'm new to Objective-C and X-code but this seems like a memory issue. I'm wondering if this is memory I need to allocate in the code (it builds fine) or if this is an issue with the program running the plugin. Any advice would be great, thanks
#define IMG_SQSIZE 262144 //(512^2)
double tmp_var[IMG_SQSIZE], tmp_var2[IMG_SQSIZE];

Answer 1

Note that 512^2 is a LOT larger than 200^2 and I suspect as you do that it is a memory issue.
You should allocate the memory using malloc and move the code to C. This is my suggestion based on the requirements - lots of memory and an array of doubles. If you could use floats or even ints here it would also dramatically reduce the resource requirements so see if that can work.
At least with Objective-C this is fairly easy to do but you should probably wrap all of this inside its own autoreleasepool as well.
Let's try the easy way first. See if the following works.
// Allocate the memory
tmp_var = malloc( IMG_SQSIZE * sizeof( double ) );
tmp_var2 = malloc( IMG_SQSIZE * sizeof( double ) );
if ( tmp_var && tmp_var2 )
{
// ... do stuff
// ... see if it works
// ... if it crashes you have trouble
// ... when done free - below
}
else
{
// Needs better handling but for now just to test
NSLog( #"Out of memory" );
}
// You must to call this, ensure you do not return
// without passing here
free ( tmp_var );
free ( tmp_var2 );
EDIT
Here is another version that does a single malloc. Not sure which will be better but worth a shot ... if memory is not a problem this one should perform better.
// Supersizeme
tmp_var = malloc( 2 * IMG_SQSIZE * sizeof( double ) );
if ( tmp_var )
{
// This points to the latter portion
tmp_var2 = tmp_var + IMG_SZSIZE;
// ... do stuff
// ... see if it works
// ... if it crashes you have trouble
// ... when done free - below
}
else
{
// Needs better handling but for now just to test
NSLog( #"Out of memory" );
}
// You must to call this, ensure you do not return
// without passing here
free ( tmp_var );
Also, in both cases, you need to define the variables as
double * tmp_var;
double * tmp_var2;