While attempting to reproduce this, I ran into another ConditionalWeakTable/sgen bug + entered it into the bug tracker. Unsure if this is related to the segv or not:<div><div><br></div><div><a href="http://bugzilla.xamarin.com/show_bug.cgi?id=1175">http://bugzilla.xamarin.com/show_bug.cgi?id=1175</a></div>
<div><br></div><div><br><br><div class="gmail_quote">On Sat, Oct 1, 2011 at 12:51 AM, Brian Luczkiewicz <span dir="ltr">&lt;<a href="mailto:brian@sooloos.com">brian@sooloos.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Before I track down a tiny repro case for this and file a formal bug report, I wanted to check and see if these stack traces look like any known bugs.<div><br></div><div>We&#39;ve recently added usage of ConditionalWeakTable&lt;,&gt; api to our codebase. We are now seeing some crashes in the mono runtime. The crashes appear to be sgen specific.</div>

<div><br></div><div>The stack traces look like this:</div><div><br></div><div><pre style="margin-right:1em;margin-left:1.6em;padding-top:2px;padding-right:2px;padding-bottom:2px;padding-left:0px;background-color:rgb(255, 255, 255);border-top-width:1px;border-right-width:1px;border-bottom-width:1px;border-left-width:1px;border-top-style:solid;border-right-style:solid;border-bottom-style:solid;border-left-style:solid;border-top-color:rgb(218, 218, 218);border-right-color:rgb(218, 218, 218);border-bottom-color:rgb(218, 218, 218);border-left-color:rgb(218, 218, 218);width:auto;overflow-x:auto;color:rgb(72, 72, 72);font-size:12px">
Stacktrace:

  at (wrapper managed-to-native) object.__icall_wrapper_mono_object_castclass (object,intptr) &lt;IL 0x00022, 0xffffffff&gt;
  at System.Runtime.CompilerServices.ConditionalWeakTable`2.TryGetValue (TKey,TValue&amp;) [0x00083] in /private/tmp/monobuild/build/BUILD/mono-2.10.5/mcs/cl... stack frames of our application code ...
  at Application.Main (string[]) [0x00622] in /Projects/sooloos/sooloos/Client/Desktop/main.cs:266
  at (wrapper runtime-invoke) &lt;Module&gt;.runtime_invoke_void_object (object,intptr,intptr,intptr) &lt;IL 0x00050, 0xffffffff&gt;

Native stacktrace:

    0   Sooloos                             0x000bc1d6 mono_handle_native_sigsegv + 422
    1   Sooloos                             0x000049fe mono_sigsegv_signal_handler + 334
    2   libsystem_c.dylib                   0x98cd559b _sigtramp + 43
    3   ???                                 0xffffffff 0x0 + 4294967295
    4   Sooloos                             0x0016be1c mono_image_lock + 29
    5   Sooloos                             0x0016bf55 mono_image_property_insert + 17
    6   Sooloos                             0x00135659 mono_class_set_failure + 84
    7   Sooloos                             0x0012c745 mono_class_init + 709
    8   Sooloos                             0x001331c4 mono_class_is_assignable_from + 109
    9   Sooloos                             0x001cc1bf mono_object_isinst + 118
    10  Sooloos                             0x0007b549 mono_object_castclass + 57
    11  ???                                 0x004bb8e8 0x0 + 4962536
    12  ???                                 0x0c848794 0x0 + 210012052
    13  ???                                 0x096fc710 0x0 + 158320400
    14  ???                                 0x077aaa80 0x0 + 125479552
    15  ???                                 0x109fdf74 0x0 + 278912884
    16  ???                                 0x109fdf34 0x0 + 278912820
    17  ???                                 0x109b5b8b 0x0 + 278616971
    18  ???                                 0x109b42e8 0x0 + 278610664
    19  ???                                 0x109dfb8e 0x0 + 278789006
    20  ???                                 0x109fb090 0x0 + 278900880
    21  ???                                 0x109fae70 0x0 + 278900336
    22  ???                                 0x109dfb8e 0x0 + 278789006
    23  ???                                 0x109fb090 0x0 + 278900880
    24  ???                                 0x109fae70 0x0 + 278900336
    25  ???                                 0x109dfb8e 0x0 + 278789006
    26  ???                                 0x109fb090 0x0 + 278900880
    27  ???                                 0x137edc24 0x0 + 327080996
    28  ???                                 0x109dfb8e 0x0 + 278789006
    29  ???                                 0x109fb090 0x0 + 278900880
    30  ???                                 0x109fae70 0x0 + 278900336
    31  ???                                 0x109dfb8e 0x0 + 278789006
    32  ???                                 0x109fb090 0x0 + 278900880
    33  ???                                 0x109fae70 0x0 + 278900336
    34  ???                                 0x109dfb8e 0x0 + 278789006
    35  ???                                 0x109fb090 0x0 + 278900880
    36  ???                                 0x109fae70 0x0 + 278900336
    37  ???                                 0x109dfb8e 0x0 + 278789006
    38  ???                                 0x109fb090 0x0 + 278900880
    39  ???                                 0x109fae70 0x0 + 278900336
    40  ???                                 0x109dfb8e 0x0 + 278789006
    41  ???                                 0x109fb090 0x0 + 278900880
    42  ???                                 0x109dfb8e 0x0 + 278789006
    43  ???                                 0x109fb090 0x0 + 278900880
    44  ???                                 0x109fae70 0x0 + 278900336
    45  ???                                 0x109dfb8e 0x0 + 278789006
    46  ???                                 0x109de264 0x0 + 278782564
    47  ???                                 0x0ca05744 0x0 + 211834692
    48  ???                                 0x0ca05506 0x0 + 211834118
    49  ???                                 0x004b32b4 0x0 + 4928180
    50  ???                                 0x004b35a3 0x0 + 4928931
    51  Sooloos                             0x00010724 mono_jit_runtime_invoke + 164
    52  Sooloos                             0x001c7815 mono_runtime_invoke + 137
    53  Sooloos                             0x001ca0f4 mono_runtime_exec_main + 669
    54  Sooloos                             0x001c942e mono_runtime_run_main + 843
    55  Sooloos                             0x0008caf0 mono_main + 8576
    56  Sooloos                             0x00002eb5 start + 53
    57  ???  </pre></div>
</blockquote></div><br></div></div>