Re: Frequent segfaults in c# running on mono

Ah, of course, thank-you!! We had seen this in the past but not for a while
now. It resurfaced when we moved to a new instance, which still had the old
kernel. D'oh. Super unfortunate that this appears to be back in 4.1 :(.

On 27 November 2015 at 23:10, Matt Calder <[email protected]> wrote:

> River,
>
> We see seg-faults in multi-threaded code on Ubuntu 14.04 and 14.10. These
> can be reproduced relatively easily. We believe it is this bug:
>
> https://bugzilla.xamarin.com/show_bug.cgi?id=29692
>
> The discussions there will lead you to some discussions about kernel
> versions. We still see this bug using 3.13 or 3.19 kernels.
>
> Matt
>
>
> On Fri, Nov 27, 2015 at 5:31 AM, River Satya <[email protected]>
> wrote:
>
>>
>>  Stack trace flavour 3:
>>
>> --
>> :Stacktrace:
>> -
>> -  at <unknown> <0xffffffff>
>> -  at (wrapper managed-to-native) System.Delegate.CreateDelegate_internal
>> (System.Type,object,System.Reflection.MethodInfo,bool) <IL 0x00010,
>> 0xffffffff>
>> -  at System.Delegate.CreateDelegate
>> (System.Type,object,System.Reflection.MethodInfo,bool,bool) <0x0071a>
>> -  at System.Delegate.CreateDelegate
>> (System.Type,object,System.Reflection.MethodInfo) <0x00021>
>> -  at System.Reflection.Emit.DynamicMethod.CreateDelegate
>> (System.Type,object) <0x00043>
>> -  at System.Linq.Expressions.Compiler.LambdaCompiler.CreateDelegate ()
>> <IL 0x00022, 0x00094>
>> -  at System.Linq.Expressions.Compiler.LambdaCompiler.Compile
>> (System.Linq.Expressions.LambdaExpression,System.Runtime.CompilerServices.DebugInfoGenerator)
>> <IL 0x0001e, 0x000d6>
>> -  at System.Linq.Expressions.Expression`1.Compile () <IL 0x00002,
>> 0x00016>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.VisitMemberAccess
>> (System.Linq.Expressions.MemberExpression) <IL 0x000fe, 0x003a6>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.Visit
>> (System.Linq.Expressions.Expression) <IL 0x000e3, 0x000e1>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.VisitBinary
>> (System.Linq.Expressions.BinaryExpression) <IL 0x0016d, 0x00736>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.Visit
>> (System.Linq.Expressions.Expression) <IL 0x000fd, 0x0016b>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.VisitLambda
>> (System.Linq.Expressions.LambdaExpression) <IL 0x0005a, 0x00169>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.Visit
>> (System.Linq.Expressions.Expression) <IL 0x000d6, 0x0009c>
>> -  at
>> ServiceStack.OrmLite.SqlExpressionVisitor`1.ProcessInternalExpression ()
>> <IL 0x0001a, 0x00073>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.And
>> (System.Linq.Expressions.Expression`1<System.Func`2<T, bool>>) <IL 0x00027,
>> 0x000f4>
>> -  at ServiceStack.OrmLite.SqlExpressionVisitor`1.Where
>> (System.Linq.Expressions.Expression`1<System.Func`2<T, bool>>) <IL 0x00005,
>> 0x00028>
>> -  at ServiceStack.OrmLite.ReadExtensions.Select<T>
>> (System.Data.IDbCommand,System.Linq.Expressions.Expression`1<System.Func`2<T,
>> bool>>) <IL 0x0000d, 0x0006e>
>> -  at
>> ServiceStack.OrmLite.ReadConnectionExtensions/<>c__DisplayClassd`1.<Select>b__c
>> (System.Data.IDbCommand) <IL 0x00007, 0x00046>
>> --
>> :Native stacktrace:
>> -
>> -       /usr/bin/mono() [0x4b23dc]
>> -       /lib/x86_64-linux-gnu/libpthread.so.0(+0x10340) [0x7fc516460340]
>> -       /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x39) [0x7fc5160c1cc9]
>> -       /lib/x86_64-linux-gnu/libc.so.6(abort+0x148) [0x7fc5160c50d8]
>> -       /usr/bin/mono() [0x629999]
>> -       /usr/bin/mono() [0x629ba7]
>> -       /usr/bin/mono() [0x629cf6]
>> -       /usr/bin/mono(mono_class_from_mono_type+0x37) [0x519b07]
>> -       /usr/bin/mono() [0x42a69a]
>> -       /usr/bin/mono() [0x42b301]
>> -       /usr/bin/mono() [0x42c89f]
>> -       /usr/bin/mono() [0x42d29b]
>> -       /usr/bin/mono() [0x5398f8]
>> -       [0x4115956d]
>> -
>> -Debug info from gdb:
>> -
>> -Could not attach to process.  If your uid matches the uid of the target
>> -process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
>> --
>>
>>
>> Stack trace flavour 4 (no non-native stacktrace):
>> These vary a bit, but look pretty much like the below.
>>
>> --
>> :Stacktrace:
>> -
>> -
>> :Native stacktrace:
>> -
>> -       /usr/bin/mono() [0x4b23dc]
>> -       /lib/x86_64-linux-gnu/libpthread.so.0(+0x10340) [0x7fb78e49c340]
>> -       /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x39) [0x7fb78e0fdcc9]
>> -       /lib/x86_64-linux-gnu/libc.so.6(abort+0x148) [0x7fb78e1010d8]
>> -       /usr/bin/mono() [0x629999]
>> -       /usr/bin/mono() [0x629ba7]
>> -       /usr/bin/mono() [0x629cf6]
>> -       /usr/bin/mono() [0x6194dc]
>> -       /usr/bin/mono() [0x422086]
>> -       /usr/bin/mono() [0x5a7012]
>> -       /usr/bin/mono() [0x5b0720]
>> -       /usr/bin/mono() [0x5a1d99]
>> -       /usr/bin/mono() [0x5a1dd0]
>> -       /usr/bin/mono() [0x5a226d]
>> -       /usr/bin/mono() [0x5875f8]
>> -       /usr/bin/mono() [0x623b66]
>> -       /lib/x86_64-linux-gnu/libpthread.so.0(+0x8182) [0x7fb78e494182]
>> -       /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7fb78e1c147d]
>> -
>>
>> On 27 November 2015 at 20:31, River Satya <[email protected]> wrote:
>>
>>> Hi mono list,
>>>
>>> We see a lot of segfaults (~10 / day) in our program running on Ubuntu
>>> Wheezy. I was hoping that upgrading to mono 4.2 would resolve it, but we're
>>> still seeing them.
>>>
>>> The stack traces take a few different forms, so it's possible that
>>> they're actually separate issues.
>>>
>>> We mostly see #1 and #4. #2 and #3 have only been seen in isolation, but
>>> have more interesting stack traces.
>>>
>>> These look to me like mono bugs. Are any of these known issues? Is there
>>> anything I can do to either work around them and/or assist in debugging
>>> them? They're currently causing significant problems in a mission critical
>>> piece of software for my client.
>>>
>>> (email split into pieces as the full version was rejected by the
>>> maillist server).
>>>
>>> Thanks,
>>>
>>> River
>>>
>>>>
>>>> Stack trace 1 (empty trace):
>>>> :Stacktrace:
>>>> -
>>>> -
>>>> :Native stacktrace:
>>>> -
>>>> Stack trace 2:
>>>> --
>>>> :Stacktrace:
>>>> -
>>>> -  at <unknown> <0xffffffff>
>>>> -  at (wrapper managed-to-native)
>>>> object.__icall_wrapper_mono_gc_alloc_vector (intptr,intptr,intptr) <IL
>>>> 0x0000f, 0xffffffff>
>>>> -  at (wrapper alloc) object.AllocVector (intptr,intptr) <IL 0x00088,
>>>> 0xffffffff>
>>>> -  at System.Xml.XmlUtf8RawTextWriter..ctor
>>>> (System.IO.Stream,System.Xml.XmlWriterSettings) <IL 0x00039, 0x000cf>
>>>> -  at System.Xml.XmlWriterSettings.CreateWriter (System.IO.Stream) <IL
>>>> 0x00067, 0x00117>
>>>> -  at System.Xml.XmlWriter.Create
>>>> (System.IO.Stream,System.Xml.XmlWriterSettings) <IL 0x0000f, 0x00066>
>>>> -  at
>>>>  <snip> rest of stack trace is in our code</snip>
>>>> --
>>>> :Native stacktrace:
>>>> -
>>>> -       /usr/bin/mono() [0x49cf0c]
>>>> -       /lib/x86_64-linux-gnu/libpthread.so.0(+0x10340) [0x7fb9e29e9340]
>>>> -       /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x39) [0x7fb9e264acc9]
>>>> -       /lib/x86_64-linux-gnu/libc.so.6(abort+0x148) [0x7fb9e264e0d8]
>>>> -       /usr/bin/mono() [0x62a329]
>>>> -       /usr/bin/mono() [0x62a537]
>>>> -       /usr/bin/mono() [0x62a5e2]
>>>> -       /usr/bin/mono() [0x5ea7a6]
>>>> -       /usr/bin/mono() [0x5ecfe0]
>>>> -       /usr/bin/mono() [0x5f5af2]
>>>> -       /usr/bin/mono() [0x5f67aa]
>>>> -       /usr/bin/mono() [0x5ecb03]
>>>> -       /usr/bin/mono() [0x5dbf76]
>>>> -       /usr/bin/mono() [0x5e380d]
>>>> -       /usr/bin/mono() [0x5f99f8]
>>>> -       /usr/bin/mono() [0x5e5f63]
>>>> -       /usr/bin/mono() [0x5e805f]
>>>> -       /usr/bin/mono() [0x5db55d]
>>>> -       /usr/bin/mono() [0x5ca11e]
>>>> --
>>>
>>>
>>>
>>>
>>
>> _______________________________________________
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>> http://lists.ximian.com/mailman/listinfo/mono-list
>>
>>
>

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