App shutdown with EXC_RESOURCE, WAKEUPS exception on iOS 8 GM

Question

Does anyone know what this kind of exception is on iOS 8?

=== from crash report ===

Exception Type: EXC_RESOURCE Exception Subtype: WAKEUPS Exception Message: (Limit 150/sec) Observed 206/sec over 300 secs Triggered by Thread: 14 

Seems to only happen on iOS 8... Our app is shut down quite randomly at arbitrary intervals with this exception..

Any clues are welcome. Thanks!

Answer 1

Your app is sending a wakeup command to a particular thread in the app quite often - apparently an average of 206 times a second. Background threads in iOS 8 have a hard limit on how many times you can run a sleep/wake cycle on each thread per second, and having a high count here is usually an indication that something is wrong / inefficient in your thread management.

Without seeing your code, my recommendation is that you check your C++ algorithms for sleep/wake calls, or multithread the background process to start new threads each cycle.

Ray Wenderlich has a fantastic tutorial on Apple's system for multithreading, Grand Central Dispactch, which might also be a good resource for you: http://www.raywenderlich.com/60749/grand-central-dispatch-in-depth-part-1