GCD should be easier to debug: backtrace

Originator:numist
Number:rdar://12578679 Date Originated:25-Oct-2012 05:29 PM
Status:Open Resolved:
Product:Developer Tools Product Version:Xcode Version 4.5.1 (4G1004)/LLDB-167.4
Classification:UI/Usability Reproducible:Always
 
Summary:
Debugging concurrency/mutexes in GCD gets harder the more you do it, especially as you make an effort to do things more asynchronously.

Example: "how did this block come to be scheduled?"

Steps to Reproduce:
- foo {
    dispatch_async(dispatch_get_global_queue(0,0), ^{
        [self bar];
    });
}

- bar {
    // breakpoint
}

Expected Results:
Some way to determine the history:
#0	0x00002005 in -[Foo bar] at /Users/.../Foo.m:28
#1	0x049ea53f in __59-[Foo foo]_block_invoke_0 at /Users/.../Foo.m:23
#2	0x049fc014 in -[Foo foo] at /Users/.../Foo.m:22


Actual Results:
#0	0x00002005 in -[Foo bar] at /Users/.../Foo.m:28
#1	0x00002105 in __59-[Foo foo]_block_invoke_0 at /Users/.../Foo.m:22
#2	0x049ea53f in _dispatch_call_block_and_release ()
#3	0x049fc014 in _dispatch_client_callout ()
#4	0x049ed2e8 in _dispatch_root_queue_drain ()
#5	0x049ed450 in _dispatch_worker_thread2 ()
#6	0x96267e12 in _pthread_wqthread ()

...what?

Comments


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