Elusive randomly occuring exceptions

[Jeff Shepler]

This is probably not the right newsgroup for this, but this is the
only one I read and there are a lot of smart people that "live" here.
Please don't berate me if you think this should have been posted in
another newsgroup.

The web application I'm currently working on will (seemingly) randomly
throw an exception when opening a database connection. Not always in
the same place. Not always the same SqlConnection object. Not always
the same anything. The application could run fine for hours or it
could crash within a couple of requests of the last one.
Here is the most common exception thrown:

[COMException (0x80070006): The handle is invalid. (Exception from
HRESULT: 0x80070006 (E_HANDLE))]

System.Runtime. InteropServices .Marshal.ThrowE xceptionForHRIn ternal(Int32
errorCode, IntPtr errorInfo) +0
System.Runtime. InteropServices .Marshal.ThrowE xceptionForHR(I nt32
errorCode) +34
System.Data.Pro viderBase.DbCon nectionPool.Get Connection(DbCo nnection
owningObject) +636

System.Data.Pro viderBase.DbCon nectionFactory. GetConnection(D bConnection
owningConnectio n) +82

System.Data.Pro viderBase.DbCon nectionClosed.O penConnection(D bConnection
outerConnection , DbConnectionFac tory connectionFacto ry) +105
System.Data.Sql Client.SqlConne ction.Open() +111
System.Data.Com mon.DbDataAdapt er.FillInternal (DataSet dataset,
DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String
srcTable, IDbCommand command, CommandBehavior behavior) +121
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet, Int32
startRecord, Int32 maxRecords, String srcTable, IDbCommand command,
CommandBehavior behavior) +137
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet) +86

What handle????
Sometimes, I get a SemephoreFullEx ception instead:

[SemaphoreFullEx ception: Adding the given count to the semaphore would
cause it to exceed its maximum count.]
System.Threadin g.Semaphore.Rel ease(Int32 releaseCount) +1853063

System.Data.Pro viderBase.DbCon nectionPool.Put NewObject(DbCon nectionInternal
obj) +54

System.Data.Pro viderBase.DbCon nectionPool.Dea ctivateObject(D bConnectionInte rnal
obj) +228

System.Data.Pro viderBase.DbCon nectionPool.Put Object(DbConnec tionInternal
obj, Object owningObject) +265

System.Data.Pro viderBase.DbCon nectionInternal .CloseConnectio n(DbConnection
owningObject, DbConnectionFac tory connectionFacto ry) +97
System.Data.Sql Client.SqlConne ction.Close() +117
System.Data.Com mon.DbDataAdapt er.QuietClose(I DbConnection
connection, ConnectionState originalState) +13
System.Data.Com mon.DbDataAdapt er.FillInternal (DataSet dataset,
DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String
srcTable, IDbCommand command, CommandBehavior behavior) +285
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet, Int32
startRecord, Int32 maxRecords, String srcTable, IDbCommand command,
CommandBehavior behavior) +137
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet) +86
Or sometimes I get:

[SqlException (0x80131904): A transport-level error has occurred when
sending the request to the server. (provider: TCP Provider, error: 0 -
An operation was attempted on something that is not a socket.)]
System.Data.Sql Client.SqlConne ction.OnError(S qlException exception,
Boolean breakConnection ) +857370
System.Data.Sql Client.SqlInter nalConnection.O nError(SqlExcep tion
exception, Boolean breakConnection ) +734982

System.Data.Sql Client.TdsParse r.ThrowExceptio nAndWarning(Tds ParserStateObje ct
stateObj) +188
System.Data.Sql Client.TdsParse rStateObject.Th rowExceptionAnd Warning()
+13
System.Data.Sql Client.TdsParse rStateObject.Wr iteSni() +638049
System.Data.Sql Client.TdsParse rStateObject.Wr itePacket(Byte
flushMode) +265
System.Data.Sql Client.TdsParse rStateObject.Ex ecuteFlush() +51
System.Data.Sql Client.TdsParse r.TdsExecuteRPC (_SqlRPC[] rpcArray,
Int32 timeout, Boolean inSchema, SqlNotification Request
notificationReq uest, TdsParserStateO bject stateObj) +3977
System.Data.Sql Client.SqlComma nd.RunExecuteRe aderTds(Command Behavior
cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean
async) +886
System.Data.Sql Client.SqlComma nd.RunExecuteRe ader(CommandBeh avior
cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String
method, DbAsyncResult result) +132
System.Data.Sql Client.SqlComma nd.RunExecuteRe ader(CommandBeh avior
cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String
method) +32
System.Data.Sql Client.SqlComma nd.ExecuteReade r(CommandBehavi or
behavior, String method) +122
System.Data.Sql Client.SqlComma nd.ExecuteDbDat aReader(Command Behavior
behavior) +12

System.Data.Com mon.DbCommand.S ystem.Data.IDbC ommand.ExecuteR eader(CommandBe havior
behavior) +7
System.Data.Com mon.DbDataAdapt er.FillInternal (DataSet dataset,
DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String
srcTable, IDbCommand command, CommandBehavior behavior) +141
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet, Int32
startRecord, Int32 maxRecords, String srcTable, IDbCommand command,
CommandBehavior behavior) +137
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet) +86

After I get any of those exceptions, any further requests that attempt
to open the connection results IIS requesting login credentials - none
of which work (including administrator) and resuts in:

[UnauthorizedAcc essException: Access is denied. (Exception from
HRESULT: 0x80070005 (E_ACCESSDENIED ))]

System.Runtime. InteropServices .Marshal.ThrowE xceptionForHRIn ternal(Int32
errorCode, IntPtr errorInfo) +0
System.Runtime. InteropServices .Marshal.ThrowE xceptionForHR(I nt32
errorCode) +34
System.Data.Pro viderBase.DbCon nectionPool.Get Connection(DbCo nnection
owningObject) +636

System.Data.Pro viderBase.DbCon nectionFactory. GetConnection(D bConnection
owningConnectio n) +82

System.Data.Pro viderBase.DbCon nectionClosed.O penConnection(D bConnection
outerConnection , DbConnectionFac tory connectionFacto ry) +105
System.Data.Sql Client.SqlConne ction.Open() +111
System.Data.Com mon.DbDataAdapt er.FillInternal (DataSet dataset,
DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String
srcTable, IDbCommand command, CommandBehavior behavior) +121
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet, Int32
startRecord, Int32 maxRecords, String srcTable, IDbCommand command,
CommandBehavior behavior) +137
System.Data.Com mon.DbDataAdapt er.Fill(DataSet dataSet) +86
This makes even less sense to me than the Invalid Handle exception.
The connection uses a SQL login, not windows auth/trusted connection.
Why, after any of the first exceptions, is the login not valid? Why is
IIS prompting for windows credentials?

This happens on both an XP/IIS5 develeopment box and a 2003/IIS6
production box. The application has it's own application pool on the
production box for now while I'm testing.

The IIS processes (aspnet on IIS5, w3wp on IIS6) will eventually
crash, but not immediately. Letting the process crash or manually
ending the process or recycling the application pool or restarting the
web service will clear the problem and all will be fine for an unknown
amount of time (could be the next request, could be the next day).

I don't know what to do. I don't know how to troubleshoot this. Days
of googling and searching forums has not helped me.

Please help!

[Peter Bromberg [C# MVP]]

Close is fine without Dispose. In fact, before a hotfix in 1.1, it was the
only way to return the connection to the pool. However, I'd consider using
the "Best practices"Patte rn: Open a connection immediately before the code
the uses it, and close it immediately thereafter. With pooling most of the
overhead of connection - related semantics is alleviated.
Peter

--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Jeff Shepler" wrote:

I do close, but not dispose. The class doesn't know how many times a
method is going to be called. I didn't want to create a new
SqlConnection instance for each method. I guess I could implement a
destructor in my facade class that would call conn.Dispose(). While
that might be preferred, I don't think it helps with these exceptions
that I'm getting.

However, I believe that if the pool was running out of connections,
I'd get a the timeout exception. Something like: Error connecting:
Timeout expired. The timeout period elapsed prior to obtaining a
connection from the pool. This may have occurred because all pooled
connections were in use and max pool size was reached.

On Tue, 4 Jul 2006 17:15:43 +0100, "Marc Gravell"
<ma**********@g mail.comwrote:

Are you saying that if user1 and user2 ask
for a connection (is the same app domain) using the exact same
connection string, they would get two different connections?

If IIS is configured to switch into the user's NT identity, then my
understanding is that yes: each user would get their own pool; the pool
maximum would probably kick in quite soon such that you don't see much
benefit from pooling, but I was mainly asking to see if you were drowning in
the connection pool. Many IIS configurations use the trusted sub-system
model, with some form of access-control at the boundary, then a single NT
identity (e.g. "NETWORK SERVICE", etc) performing all access within the
system; as I understand it this will allow the pool to be shared across all
users.

I'm still not sure that this would explain the level of errors that you are
seeing; are you /sure/ the connections are closed and disposed
appropriately?

Marc