How to break on __NSAutoreleaseNoPool - debugging

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.

Answer 2

I have the same issue on setting breakpoint on __NSAutoreleaseNoPool().
I finally successfully set the break point use gdb command.
After debugger started, press ctrl+C in debugger console.
Use "br __NSAutoreleaseNoPool" to set the break point and restart the debugger.

Answer 3

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?

Answer 4

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 5

I know this is an old thread. Just wanted to share some light on the right solution.
The right way to have a breakpoint at _autoreleasenopool is using the breakpoint navigator in xcode.(use the key command+6).
In the bottom left portion of the breakpoint navigator click '+' sign and add symbolic breaakpoint. Enter the symbol as objc_autoreleaseNoPool.