We use an embedded firebird database through the .NET data provider. We get periodically access violations when beginning a transaction (this may be called in parallel by several threads).

We use the FirebirdSql.Data.FirebirdClient .NET data provider, compiled by us from scratch on .NET 4.

The stack trace follows:
Unhandled Exception: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other me
mory is corrupt.
   at FB_965910463_Class.isc_start_multiple(IntPtr[] statusVector, Int32& trHandle, Int16 dbHandleCount, IntPtr tebVectorAddress)
   at FB_965910463_Class.IFbClient.isc_start_multiple(IntPtr[] statusVector, Int32& trHandle, Int16 dbHandleCount, IntPtr tebVectorAddress)
   at FirebirdSql.Data.Client.Native.FesTransaction.BeginTransaction(TransactionParameterBuffer tpb) in c:\dev\3rd_party\Firebird\Firebird.N
ET\Client\Native\FesTransaction.cs:line 180
   at FirebirdSql.Data.Client.Native.FesDatabase.BeginTransaction(TransactionParameterBuffer tpb) in c:\dev\3rd_party\Firebird\Firebird.NET\
Client\Native\FesDatabase.cs:line 333
   at FirebirdSql.Data.FirebirdClient.FbTransaction.BeginTransaction() in c:\dev\3rd_party\Firebird\Firebird.NET\FirebirdClient\FbTransactio
n.cs:line 363
   at FirebirdSql.Data.FirebirdClient.FbCommand.Prepare(Boolean returnsSet) in c:\dev\3rd_party\Firebird\Firebird.NET\FirebirdClient\FbComma
nd.cs:line 1114
   at FirebirdSql.Data.FirebirdClient.FbCommand.ExecuteCommand(CommandBehavior behavior, Boolean returnsSet) in c:\dev\3rd_party\Firebird\Fi
rebird.NET\FirebirdClient\FbCommand.cs:line 1176
   at FirebirdSql.Data.FirebirdClient.FbCommand.ExecuteReader(CommandBehavior behavior) in c:\dev\3rd_party\Firebird\Firebird.NET\FirebirdCl
ient\FbCommand.cs:line 538
   at FirebirdSql.Data.FirebirdClient.FbCommand.ExecuteDbDataReader(CommandBehavior behavior) in c:\dev\3rd_party\Firebird\Firebird.NET\Fire
birdClient\FbCommand.cs:line 620
   at System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader()
   at NHibernate.AdoNet.AbstractBatcher.ExecuteReader(IDbCommand cmd) in c:\Dev\3rd_party\NHibernate\NHibernate\AdoNet\AbstractBatcher.cs:li
ne 235
   at NHibernate.Loader.Loader.GetResultSet(IDbCommand st, Boolean autoDiscoverTypes, Boolean callable, RowSelection selection, ISessionImpl
ementor session) in c:\Dev\3rd_party\NHibernate\NHibernate\Loader\Loader.cs:line 1292
   at NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) in c:\Dev\3rd_pa
rty\NHibernate\NHibernate\Loader\Loader.cs:line 401
   at NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean
returnProxies) in c:\Dev\3rd_party\NHibernate\NHibernate\Loader\Loader.cs:line 236
   at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) in c:\Dev\3rd_party\NHibernate\NHibernat
e\Loader\Loader.cs:line 1644
   at NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters) in c:\Dev\3rd_party\NHiber
nate\NHibernate\Loader\Loader.cs:line 1568
   at NHibernate.Loader.Loader.List(ISessionImplementor session, QueryParameters queryParameters, ISet`1 querySpaces, IType[] resultTypes) i
n c:\Dev\3rd_party\NHibernate\NHibernate\Loader\Loader.cs:line 1562
   at NHibernate.Loader.Criteria.CriteriaLoader.List(ISessionImplementor session) in c:\Dev\3rd_party\NHibernate\NHibernate\Loader\Criteria\
CriteriaLoader.cs:line 73
   at NHibernate.Impl.SessionImpl.List(CriteriaImpl criteria, IList results) in c:\Dev\3rd_party\NHibernate\NHibernate\Impl\SessionImpl.cs:l
ine 1929
   at NHibernate.Impl.CriteriaImpl.List(IList results) in c:\Dev\3rd_party\NHibernate\NHibernate\Impl\CriteriaImpl.cs:line 246
   at NHibernate.Linq.NHibernateExtensions.List(ISession session, String entityName, Expression expr, IList list) in c:\dev\3rd_party\NHiber
nate\NHibernate.Linq\NHibernateExtensions.cs:line 69
   at Shunra.Infra.DAL.NHibernate.StatementScope.GetByExpression[TType](Expression expr, IList list) in c:\dev\windows\Infra\Shunra.Infra.DA
L.NHibernate\StatementScope.cs:line 232
   at Shunra.Infra.DAL.NHibernate.EntityTypeInfoItem.GetByExpression[TType](StatementScope ss, Expression ex, IList list) in c:\dev\windows\
Infra\Shunra.Infra.DAL.NHibernate\DataContext.cs:line 97
   at Shunra.Infra.DAL.NHibernate.StatementScope.GetByExpression(Type type, Expression expr, IList list) in c:\dev\windows\Infra\Shunra.Infr
a.DAL.NHibernate\StatementScope.cs:line 285
   at NetworkCatcher.Entities.Agent.Server.ExploreEndpointCommandFactory.Execute(ExploreEndpointDataCommand cmd) in c:\dev\windows\NC\NC.Ent
ities.Agent.Server\ExploreEndpointCommandFactory.cs:line 31
   at lambda_method(Closure , Object , Object[] )
   at Csla.Reflection.MethodCaller.CallMethod(Object obj, DynamicMethodHandle methodHandle, Object[] parameters) in c:\dev\3rd_party\csla\Re
flection\MethodCaller.cs:line 436
   at Csla.Reflection.MethodCaller.CallMethod(Object obj, String method, Object[] parameters) in c:\dev\3rd_party\csla\Reflection\MethodCall
er.cs:line 349
   at Csla.Server.FactoryDataPortal.InvokeMethod(String factoryTypeName, String methodName, Object e, DataPortalContext context) in c:\dev\3
rd_party\csla\Server\FactoryDataPortal.cs:line 77
   at Csla.Server.FactoryDataPortal.Update(Object obj, DataPortalContext context) in c:\dev\3rd_party\csla\Server\FactoryDataPortal.cs:line
164
   at Csla.Server.DataPortalSelector.Update(Object obj, DataPortalContext context) in c:\dev\3rd_party\csla\Server\DataPortalSelector.cs:lin
e 110
   at Csla.Server.DataPortal.Update(Object obj, DataPortalContext context) in c:\dev\3rd_party\csla\Server\DataPortal.cs:line 287
   at Csla.Server.Hosts.WcfPortal.Update(UpdateRequest request) in c:\dev\3rd_party\csla\Server\Hosts\WcfPortal.cs:line 85
   at Shunra.Common.Csla.WcfPortal.Update(UpdateRequest request) in C:\dev\windows\Common\Shunra.Common\Csla\WcfPortal.cs:line 41
   at SyncInvokeUpdate(Object , Object[] , Object[] )
   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)
   at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage41(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)
   at System.ServiceModel.Dispatcher.ChannelHandler.DispatchAndReleasePump(RequestContext request, Boolean cleanThread, OperationContext cur
rentOperationContext)
   at System.ServiceModel.Dispatcher.ChannelHandler.HandleRequest(RequestContext request, OperationContext currentOperationContext)
   at System.ServiceModel.Dispatcher.ChannelHandler.AsyncMessagePump(IAsyncResult result)
   at System.ServiceModel.Dispatcher.ChannelHandler.OnAsyncReceiveComplete(IAsyncResult result)
   at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
   at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
   at System.Runtime.InputQueue`1.AsyncQueueReader.Set(Item item)
   at System.Runtime.InputQueue`1.EnqueueAndDispatch(Item item, Boolean canDispatchOnThisThread)
   at System.Runtime.InputQueue`1.EnqueueAndDispatch(T item, Action dequeuedCallback, Boolean canDispatchOnThisThread)
   at System.ServiceModel.Channels.SingletonChannelAcceptor`3.Enqueue(QueueItemType item, Action dequeuedCallback, Boolean canDispatchOnThis
Thread)
   at System.ServiceModel.Channels.HttpChannelListener.HttpContextReceived(HttpRequestContext context, Action callback)
   at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContextCore(IAsyncResult result)
   at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContext(IAsyncResult result)
   at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
   at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
   at System.Net.ListenerAsyncResult.WaitCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
   at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)