debugging - 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

To actually answer your question, look in NSDebug.h. There you will find a comment of which this is part:

NAME OF ENV. VARIABLE                  DEFAULT  SET TO...
NSDebugEnabled                            NO    "YES"
NSZombieEnabled                           NO    "YES"
NSDeallocateZombies                       NO    "YES"
NSHangOnUncaughtException                 NO    "YES"

and farther down are these comments:

// Functions used as interesting breakpoints in a debugger
// void __NSAutoreleaseNoPool(void *object);
        // Called to log the "Object X of class Y autoreleased with no
        // pool in place - just leaking" message.  If an environment
        // variable named "NSAutoreleaseHaltOnNoPool" is set with string
        // value "YES", the function will automatically break in the
        // debugger (or terminate the process).

// void __NSAutoreleaseFreedObject(void *freedObject);
        // Called when a previously freed object would be released
        // by an autorelease pool.  If an environment variable named
        // "NSAutoreleaseHaltOnFreedObject" is set with string value
        // "YES", the function will automatically break in the debugger
        // (or terminate the process).

So you don't really need to set these breakpoints; just set the appropriate environment variables. You can do the latter either from your e.g. .bashrc or in Xcode 4 you can edit the "Run" section of your "scheme" and set them there -- that's what I do, and it works just fine.