title: Crash in autoreleasePool drain
body: <p>I have a rare <strong>(anonymous namespace)::AutoreleasePoolPage::pop(void*)</strong> crash in [pool drain]. As I understand its caused by over-release of some object owned by the autorelease pool.</p>
  
  <p>I tried using NSZombieEnabled = YES, and using Instruments with zombie tracer. The bug is not reproducible with these. There is no over-release message logged in the console and zombie tracer do not show any zombie alerts. But the crash is reproducible very frequently when I take off these flags. Anybody seen similar behaviour?</p>
  
  <p>Is there any other way to debug this easily? I am using Xcode 5.0.1 in OS 10.8.5. I am pasting the crashed thread trace below:</p>
  
  <p>Exception Type:  EXC_BAD_ACCESS (SIGSEGV)</p>
  
  <p>Exception Codes: EXC_I386_GPFLT</p>
  
  <p>Application Specific Information:
  objc_msgSend() selector name: release</p>
  
  <blockquote>
    <p>0   libobjc.A.dylib                   0x00007fff8b3040a3 objc_msgSend +35</p>
    
    <p>1   com.apple.CoreFoundation          0x00007fff855d086f CFRelease + 591</p>
    
    <p>2   com.apple.CoreFoundation          0x00007fff856028a9
    -[__NSDictionaryM dealloc] + 249</p>
    
    <p>3   libobjc.A.dylib                   0x00007fff8b30665a (anonymous
    namespace)::AutoreleasePoolPage::pop(void*) + 502</p>
    
    <p>4   com.apple.ist.istcore             0x000000010fb91d82
    -[SomeFileOperation main] + 117</p>
    
    <p>5   com.apple.Foundation              0x00007fff81f2070b
    <strong>NSThread__main</strong> + 1318</p>
    
    <p>6   libsystem_pthread.dylib           0x00007fff86389899 _pthread_body +
    138</p>
    
    <p>7   libsystem_pthread.dylib           0x00007fff8638972a _pthread_start +
    137</p>
    
    <p>8   libsystem_pthread.dylib           0x00007fff8638dfc9 thread_start +
    13</p>
  </blockquote>
  
  <p>Thanks in advance.</p>