How to break on __NSAutoreleaseNoPool

Question

I'm getting peppered with

* __NSAutoreleaseNoPool(): Object 0x1961180 of class NSEvent autoreleased with no pool in place - just leaking

warnings during run-time and have no idea what the cause is. Cursory Googles indicate that this is a symbol I can break on with Xcode, but adding it as a symbolic breakpoint via Run>Manage Breakpoints>Add Symbolic Breakpoint, or simply via the breakpoints management window, results in a breakpoint with a - next to it instead of a check, which I take to mean it's a symbol that can't be found.

I've tried adding the symbol "__NSAutoreleaseNoPool" with two underscores, one underscore, and now I'm just feeling stupid. The errors continue to get logged and no breakpoints get hit. Any pointers for breaking on Obj-C symbols or debugging this would be appreciated.

[EDIT: after maybe 10 (10 more, so a couple dozen total, including at least two Xcode restarts) runs I got "Pending breakpoint 9 - "__NSAutoreleaseNoPool" resolved" printed to my console and the breakpoint started working. Is there any way to force a pending breakpoint to actually resolve?]

Answer 1

The issue here is simple: You are releasing with no pool in place. This usually happens in command line tools written against Foundation. Simply add the following code to your main(): (Irrelevant parts omitted)

int main (…) {
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

  /// Your code goes here.

  [pool drain]; // This one might not strictly speaking be neccessary.
  [pool release];

   return 0;
}

Edit: If you are not creating a command line tool, chances are you are doing something naughty; but nonetheless: If you have code you invoke before NSApplicationMain(), you need to wrap this in the same basic code, draining and releasing the pool before the invocation of NSApplicationMain.

Answer 2

It sounds like you're using Cocoa in a thread somewhere and not wrapping the thread body with an autorelease pool. You probably don't need to use breakpoints to find this. Are you doing any detachNewThreadSelector?