Question

I’m developing an app for the App Store, and having strange issues with memory management.

I am using ARC.

When testing my app on an unjailbroken iPod touch 4G 6.0.1 connected to Instruments, everything seems to go fine – my app uses less than 5mb of memory all the time and there are no leaks. However, after long usage, despite still being monitored in instruments as < 5Mb, i begin getting memory warnings and finally am killed by the OS. I do not have any open apps in the background, so i am assuming that my app is leaking memory instrumants cannot track. How can this be?

Further, i begun using a function to track memory usage, specyfically:

 struct task_basic_info info;
    mach_msg_type_number_t size = sizeof(info);
    kern_return_t kerr = task_info(mach_task_self(),
                                   TASK_BASIC_INFO,
                                   (task_info_t)&info,
                                   &size);
    if( kerr == KERN_SUCCESS ) {
        return info.resident_size/1024.0/1024.0;
    } else {
        return -1.0;
    }

and it seems to report memory usage in range that could be expected by my app’s behaviour (60-70Mb). I do measurements simultaneously in Instruments and it still shows ~3-4Mb. What is going on here?

Answer 1

The Allocations instrument only track Heap memories, it’s just a small part of memory usage to the whole runnning application.

Take a look at the VM Tracker instrument, that is the whole virtual memory usage statistics, and maybe you can find the problem.