Re: App Crashes When Built with Xcode 3.2.5
Re: App Crashes When Built with Xcode 3.2.5
- Subject: Re: App Crashes When Built with Xcode 3.2.5
- From: Simon Wilson <email@hidden>
- Date: Mon, 17 Jan 2011 23:57:02 +0100
Hi Joar,
Many thanks for the suggestions.
> Please show another couple of frames from the bracktrace. In your eyes, does the rest of the backtrace look like you expect?
Absolutely. The backtrace is expected. It contains 2 frames of application functions invoked on a background thread using NSThread detach.
The crash occurs in about 60% of test runs. While the crash is not 100% reproduceable, every crash (we've logged dozens) has exactly the same backtrace.
There is no indication of random stack or heap corruption. Whatever is causing the crash appears to be deterministic, with any variation most likely introduced through timing.
By the way, my original post contained the following line:
> but we are building for garbage collection (the "Garbage Collection" build setting is set to the default: "Unsupported")
This should have read "but we are *not* building for garbage collection". Sorry if this wasn't clear.
> And this is comparing two binaries compiled with different versions of Xcode running on the same Mac OS X 10.5 machine, or on different machines?
Yes. Both binaries were built against the 10.5 SDK on the same 10.6 machine (with the only variable being the Xcode version) and deployed and tested to the same 10.5 machine. The binaries built with both Xcode versions run fine in 64-bit mode on 10.6.
The 10.5 machine is an Intel Mac. We haven't tested the 3.2.5-generated binaries on a 32-bit 10.6 machine.
I have verified that the 10.5 machine is running no hacks/input managers/haxies etc.
> Does it still crash if you build with GCC 4.2?
This will take some time to investigate (the project is composed of about 20 separate Xcode projects) but is definitely something we will look into.
> Please verify that it still builds the way you expect with 3.2.5 by auditing the raw build transcript
Good idea. We will take a look at the build transcripts. Otherwise, the project builds without a single error or warning on both 3.2.1 and 3.2.5 (compiler warning settings are set to the defaults in both cases).
Many thanks,
Simon
On Jan 17, 2011, at 17:55 PM, Joar Wingfors wrote:
Hello Simon,
Please find some comments and questions inline below:
On 17 jan 2011, at 07.42, Simon Wilson wrote:
> Our application is crashing with the following two functions at the top of the stack trace:
>
> 0 libobjc.A.dylib 0x93b01b19 _objc_fatal + 95
> 1 libobjc.A.dylib 0x93b05e49 objc_set_collection_threshold + 0
Please show another couple of frames from the bracktrace. In your eyes, does the rest of the backtrace look like you expect?
> "objc_set_collection_threshold" would seem to be related to garbage collection, but we are building for garbage collection (the "Garbage Collection" build setting is set to the default: "Unsupported"), so it's strange that it should be calling _objc_fatal at this point.
>
> The application only crashes on Mac OS X 10.5 Leopard. The crash does not occur on Snow Leopard.
>
> But most interestingly (and the reason why I'm posting this here): the application only crashes when built with 3.2.5. The exact same code built with 3.2.1 does not crash.
And this is comparing two binaries compiled with different versions of Xcode running on the same Mac OS X 10.5 machine, or on different machines? Just to verify that you're indeed comparing apples to apples, so to speak.
> Can anybody shed some light on why our application is crashing in objc_set_collection_threshold?
>
> * Is this possibly related to garbage collection?
> * How might Xcode 3.2.5 be building our application differently from 3.2.1?
> * Did Apple change the default values of any build settings after 3.2.1?
Please verify that it still builds the way you expect with 3.2.5 by auditing the raw build transcript (available via the contextual menu in the build log). Check that the expected build settings (including GC and SDK settings) are passed to the build commands.
> We're building against the 10.5 SDK with Clang LLVM 1.0.
Does it still crash if you build with GCC 4.2?
j o a r
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