title: what does "__workq_kernreturn" indicate in an iOS crash log or when you pause execution of an app?
body: <p>When debugging on iOS, if I pause execution I often see multiple references to "__workq_kernreturn". </p>
  
  <p>If my app happens to crash, I often see multiple threads identified as below:  </p>
  
  <pre><code>Thread 19:
  0   libsystem_kernel.dylib              0x332d0cd4 __workq_kernreturn + 8
  
  Thread 20:
  0   libsystem_kernel.dylib              0x332d0cd4 __workq_kernreturn + 8
  
  Thread 21:
  0   libsystem_kernel.dylib              0x332d0cd4 __workq_kernreturn + 8
  </code></pre>
  
  <p>Does "__workq_kernreturn" indicate a thread that is waiting to exit, or a thread that is deadlocked? Is this something to be worried about?</p>