[Mono-osx] [MonoMac] Frequent SIGSEGVs in ObjCRuntime.Messaging with WebView

[Alexander Shulgin]

Hi,

I've started getting a lot of these SIGSEGVs recently, so I'd be glad 
for some help on tracking them down.

Some details: we have a C# app on OS X with Carbon(!) event loop (you 
can spot it in the native stack trace below), which uses MonoMac to bind 
some Cocoa views, currently only WebView.

Everything is just fine, except I get like 4 crashes out of 5 runs now.

I've took a brief look at MonoMac_Disposer but didn't find anything fishy.

I was using mono-2.8.0, so I've upgraded to 2.8.1, but this didn't 
change a thing.  Also, I'm using up-to-date monomac & maccore checkouts 
from github.

What can I try to debug this problem?

--
Regards,
Alex

PS: and here is a typical stack trace:

   at (wrapper managed-to-native) 
MonoMac.ObjCRuntime.Messaging.void_objc_msgSendSuper (intptr,intptr) 
<0x00003>
   at (wrapper managed-to-native) 
MonoMac.ObjCRuntime.Messaging.void_objc_msgSendSuper (intptr,intptr) 
<0x00003>
   at MonoMac.Foundation.NSObject/MonoMac_Disposer.Drain 
(MonoMac.Foundation.NSObject) [0x00026] in 
/Users/user/Projects/mono/monomac/src/Foundation/NSObject.cs:345
   at (wrapper dynamic-method) 
object.dab36271-63bc-440c-b34e-0fba4a320f8d 
(MonoMac.Foundation.NSObject,MonoMac.ObjCRuntime.Selector,MonoMac.Foundation.NSObject) 
<IL 0x0000c, 0x00030>
   at (wrapper native-to-managed) 
object.dab36271-63bc-440c-b34e-0fba4a320f8d 
(MonoMac.Foundation.NSObject,MonoMac.ObjCRuntime.Selector,MonoMac.Foundation.NSObject) 
<IL 0x00065, 0x000df>

Native stacktrace:

	0   mono                                0x000c8f5a 
mono_handle_native_sigsegv + 343
	1   mono                                0x0000ffa5 
mono_sigsegv_signal_handler + 306
	2   libSystem.B.dylib                   0x981e946b _sigtramp + 43
	3   ???                                 0xffffffff 0x0 + 4294967295
	4   WebKit                              0x92d2287a -[WebArchive 
dealloc] + 42
	5   ???                                 0x1740796c 0x0 + 390101356
	6   ???                                 0x1aa246ad 0x0 + 446842541
	7   ???                                 0x02e2d0d9 0x0 + 48419033
	8   ???                                 0x02e17ee8 0x0 + 48332520
	9   Foundation                          0x99398db9 
__NSThreadPerformPerform + 506
	10  CoreFoundation                      0x94c7d4cb 
__CFRunLoopDoSources0 + 1563
	11  CoreFoundation                      0x94c7af8f __CFRunLoopRun + 1071
	12  CoreFoundation                      0x94c7a464 CFRunLoopRunSpecific 
+ 452
	13  CoreFoundation                      0x94c7a291 CFRunLoopRunInMode + 97
	14  HIToolbox                           0x96416f9c 
RunCurrentEventLoopInMode + 392
	15  HIToolbox                           0x96416c8d 
ReceiveNextEventCommon + 158
	16  HIToolbox                           0x9659f130 _AcquireNextEvent + 54
	17  HIToolbox                           0x96594dec 
RunApplicationEventLoop + 228
	18  ???                                 0x02f798a3 0x0 + 49780899
	19  ???                                 0x02a82df0 0x0 + 44576240
	20  ???                                 0x004cbf34 0x0 + 5029684
	21  ???                                 0x004cc1e4 0x0 + 5030372
	22  mono                                0x0000fd70 
mono_jit_runtime_invoke + 1339
	23  mono                                0x001de701 mono_runtime_invoke 
+ 138
	24  mono                                0x001e08ac 
mono_runtime_exec_main + 669
	25  mono                                0x001dfc96 
mono_runtime_run_main + 814
	26  mono                                0x0009c762 mono_jit_exec + 200
	27  mono                                0x0009c99c main_thread_handler 
+ 558
	28  mono                                0x0009ecd3 mono_main + 7577
	29  mono                                0x00003a95 
mono_main_with_options + 539
	30  mono                                0x00003b1c main + 49
	31  mono                                0x0000384e start + 54

Debug info from gdb:

/tmp/mono-gdb-commands.eb91K4:1: Error in sourced command file:
unable to debug self