Stacktrace error
Hi,
I've some problem with that:

```
Stacktrace:
  at <unknown> <0xffffffff>
  at (wrapper managed-to-native) object.__icall_wrapper_mono_gc_alloc_vector (intptr,intptr,intptr) [0x00000] in <71d8ad678db34313b7f718a414dfcb25>:0
  at (wrapper alloc) object.AllocVector (intptr,intptr) <0x0014b>
  at System.Collections.Concurrent.ConcurrentQueue`1/Segment<T_REF>..ctor (int) [0x00006] in <71d8ad678db34313b7f718a414dfcb25>:0
  at System.Collections.Concurrent.ConcurrentQueue`1<T_REF>.EnqueueSlow (T_REF) [0x00051] in <71d8ad678db34313b7f718a414dfcb25>:0
  at System.Collections.Concurrent.ConcurrentQueue`1<T_REF>.Enqueue (T_REF) [0x00010] in <71d8ad678db34313b7f718a414dfcb25>:0
  at Server.MainClass.PoolReceiveCallback (Server.Client,System.Collections.Generic.Dictionary`2<string, object>,Server.CcHashset`1<string>) [0x000c9] in <e06e98ebf6b1434e84f677bc43498c7e>:0
  at Server.PoolConnectionFactory.ReceiveCallback (System.IAsyncResult) [0x00455] in <e06e98ebf6b1434e84f677bc43498c7e>:0
  at System.Net.Sockets.SocketAsyncResult/<>c.<Complete>b__27_0 (object) [0x0000b] in <fc308f916aec4e4283e0c1d4b761760a>:0
  at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem () [0x00008] in <71d8ad678db34313b7f718a414dfcb25>:0
  at System.Threading.ThreadPoolWorkQueue.Dispatch () [0x00074] in <71d8ad678db34313b7f718a414dfcb25>:0
  at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback () [0x00000] in <71d8ad678db34313b7f718a414dfcb25>:0
  at (wrapper runtime-invoke) <Module>.runtime_invoke_bool (object,intptr,intptr,intptr) [0x0001e] in <71d8ad678db34313b7f718a414dfcb25>:0
/proc/self/maps:
00400000-00826000 r-xp 00000000 fe:05 284834                             /usr/bin/mono-sgen
00a26000-00a2d000 r--p 00426000 fe:05 284834                             /usr/bin/mono-sgen
00a2d000-00a32000 rw-p 0042d000 fe:05 284834                             /usr/bin/mono-sgen
00a32000-00a49000 rw-p 00000000 00:00 0 
015d3000-01993000 rw-p 00000000 00:00 0                                  [heap]
404aa000-4056e000 rwxp 00000000 00:00 0 
41505000-41515000 rwxp 00000000 00:00 0 
7f5b51118000-7f5b5191c000 rw-p 00000000 00:00 0 
7f5b5191c000-7f5b51925000 ---p 00000000 00:00 0 
7f5b51925000-7f5b621a0000 rw-p 00000000 00:00 0                          [stack:32226]
7f5b621b8000-7f5b621bc000 rw-p 00000000 00:00 0 
7f5b621c4000-7f5b621cc000 rw-p 00000000 00:00 0 
```

each two days I've that problem.

@notgiven688, do you know how to resolve it?