Do NSThread have same memory privileges as main thread?

I'm using NSOperationQueue to manage a phase of an iOS application which is quite long so I would like to manage it asynchronously. Inside that phase I allocate big arrays in C by using directly calloc functions. With big I mean a 1024x256 bidimensional array of floats and similar things.

If everything resides on the main thread than the app locks up while computing but everything goes fine, if, instead, I move the heavy part to a NSInvocationOperation then I got many strange results, with debugger sometimes I get a strange 开发者_开发问答message in console stating

No memory available to program now: unsafe to call malloc

so I was wondering if threads managed by an operation queue have some different restrictions compared to main thread, and in case what is better to do to get around this issue.

There's no restrictions that I know of.. however, you may be hitting the edge of available RAM. Since iOS doesn't do virtual memory, when memory gets low, it'll send a warning to other apps to free up RAM. That may be the source of your issue.

Use instruments to profile how much RAM you're using. If it's more than about 20MB or so, you're probably in danger of being terminated due to excessive memory usage anyway.