[Mono-list] Help debugging program failing randomly

Ian Norton ian.norton-badrul at thales-esecurity.com
Mon Apr 8 07:42:21 UTC 2013

I'd be sure to check your struct packing and call conventions properly. And
perhaps be sure that you aren't passing in any "ref System.String" instead of


On Mon, Apr 08, 2013 at 04:21:32AM +0100, Danny wrote:
> Hello,
> I'm having a difficult time with an application I have written.  I 
> recently made some changes and I'm having a problem with it failing at 
> seemingly random times and locations (within the code), with sigsegv 
> errors.  This is a multithreaded plugin-style daemon/service (can be 
> launched from CLI) and I recently added a new component to it to poll a 
> data acquisition board via USB using FTDI.
> Almost all of our integrations like this use a shared library (or DLL on 
> Windows) and p/invoke to access hardware.  I have done dozens of these 
> integrations over USB without a persistent issue like this.  But still 
> at first I suspected this new component, as I had initially thought it 
> was trashing RAM because of the problems I had developing the shared library
> However, at the same time as I made this addition, I was also (somewhat) 
> forced to upgrade our base OS to the latest LTS Ubuntu 12.04 (was on 
> 10.04).  So unfortunately, I have more than one variable changing at a 
> time.  So I confirmed, with a configuration that eliminates the newly 
> developed component, that this problem occurs without that running.
> That's good and bad, since now it seems likely that the offending code 
> is out of my control.  I am hoping to get some information on the 
> error(s) I was able to capture, or some advice on how to debug the root 
> cause of this problem.
> I have a couple of stack traces captured and I'll include what I believe 
> is the crucial part of one here.  It's worth noting that not all of the 
> stack traces are the same.  It's also worth noting that I have seen 
> libgdiplus.so in other traces that I didn't get captured.
> I tried setting up a 10.04 machine to test with, but one of our newer 
> dependencies (ServiceStack) introduced a class that is not in the 
> default mono on that platform, giving a startup error trying to resolve 
> the IgnoreDataMemberAttribute class.  So I then got the latest mono set 
> up on that machine now, but fear that this will result in the same error 
> I am reporting (ie: I believe this to be a mono problem), since it 
> should be the same mono framework running there.
> Any help is greatly appreciated.
> <snip - a bunch of standard output msgs from the service />
> Stacktrace:
>    at (wrapper managed-to-native) System.Drawing.GDIPlus.GdipDeleteFont 
> (intptr) <0xffffffff>
>    at System.Drawing.Font.Dispose () <0x0002b>
>    at (wrapper remoting-invoke-with-check) System.Drawing.Font.Dispose 
> () <0xffffffff>
>    at System.Drawing.Font.Finalize () <0x00013>
>    at (wrapper runtime-invoke) 
> object.runtime_invoke_virtual_void__this__ (object,intptr,intptr,intpt$
> Native stacktrace:
>          mono() [0x80e16fc]
>          mono() [0x81209fc]
>          mono() [0x806094d]
>          [0xb770240c]
> /usr/lib/i386-linux-gnu/libfontconfig.so.1(FcCharSetDestroy+0x15) 
> [0xb4b1b9b5]
>          /usr/lib/i386-linux-gnu/libfontconfig.so.1(+0x17b43) [0xb4b29b43]
> /usr/lib/i386-linux-gnu/libfontconfig.so.1(FcPatternDestroy+0x82) 
> [0xb4b29e12]
>          /usr/lib/libgdiplus.so.0(GdipDeleteFontFamily+0x132) [0xb5004642]
>          /usr/lib/libgdiplus.so.0(GdipDeleteFont+0x2c) [0xb500510c]
>          [0xaf711940]
>          [0xaf7118cc]
>          [0xaf711870]
>          [0xaf7117ec]
>          [0xb5cddf41]
>          mono() [0x8150107]
> <snip - 42 thread stack details>
> =================================================================
> Got a SIGSEGV while executing native code. This usually indicates
> a fatal error in the mono runtime or one of the native libraries
> used by your application.
> =================================================================
> Danny
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