Open Operation Timeout - WCF web service - asp.net-mvc

Question

I've create a web service. After being up for a period of time, I eventually get the follow error: "The open operation did not complete within the allotted timeout of 00:01:00. The time allotted to this operation may have been a portion of a longer timeout."
I'm unsure why I'm getting this error since I've set the open timeout to about 2 hours. I'm new to WCF web services and web services in general. Is there any red flags with the configuration I've shown below?
.NET version: 4.0
Client-side configuration:
<system.serviceModel>
<bindings>
<netTcpBinding>
<binding name="SecurityServiceDev" receiveTimeout="02:00:00" openTimeout="02:00:00" maxBufferPoolSize="2147483647" maxReceivedMessageSize="2147483647" maxConnections="1000" maxBufferSize="2147483647">
<security mode="Transport">
<transport clientCredentialType="Windows" />
</security>
</binding>
</netTcpBinding>
</bindings>
<diagnostics>
<messageLogging logEntireMessage="true" maxMessagesToLog="300" logMessagesAtServiceLevel="true" logMalformedMessages="true" logMessagesAtTransportLevel="true" />
</diagnostics>
<client>
<endpoint address="net.tcp://XXX.svc" binding="netTcpBinding" bindingConfiguration="SecurityServiceDev" contract="SecurityProxy.ISecurityService" name="SecurityService" />
</client>
Web Service Configuration:
<system.serviceModel>
<services>
<service name="TMS.DAL.Common.Security.BAL.SecurityService" behaviorConfiguration="DataServiceBehavior">
<endpoint address="net.tcp://XXX.svc"
name="SecurityService"
binding="netTcpBinding"
bindingConfiguration="Binding"
contract="TMS.DAL.Common.Security.BAL.ISecurityService"/>
<endpoint contract="IMetadataExchange" binding="mexHttpBinding" address="mex" />
</service>
</services>
<bindings>
<netTcpBinding>
<binding name="Binding"
receiveTimeout="02:00:00"
openTimeout="02:00:00"
maxBufferPoolSize="2147483647"
maxReceivedMessageSize="2147483647"
maxConnections="1000"
maxBufferSize="2147483647">
<security mode="Transport">
<transport clientCredentialType="Windows"/>
</security>
</binding>
</netTcpBinding>
</bindings>
<client/>
<behaviors>
<serviceBehaviors>
<behavior name="DataServiceBehavior" >
<serviceDebug includeExceptionDetailInFaults="true"/>
<serviceMetadata httpGetEnabled="true" />
<dataContractSerializer maxItemsInObjectGraph="61200000" />
<serviceThrottling maxConcurrentCalls="1000"
maxConcurrentInstances="2147483647" maxConcurrentSessions="1000"/>
</behavior>
</serviceBehaviors>
</behaviors>
The only configuration inside the code is the following:
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class SecurityService : ISecurityService
Service Contract:
[ServiceContract]
public interface ISecurityService
{
[OperationContract]
bool IsUserInRole(String userName, String roleName);
[OperationContract]
bool DoesUserHavePermission(String userName, String permissionName);
[OperationContract]
List<String> GetUsersInRole(String roleName);
[OperationContract]
List<String> GetRolesForUser(String userName);
[OperationContract]
List<String> GetPermissionsForUser(String userName);
[OperationContract]
List<String> GetPermissionsForRole(String roleName);
[OperationContract]
List<String> GetRolesForApplication(String appName);
[OperationContract(Name = "GetListValuesForRoleAndList")]
List<String> GetListValues(String roleName, String listNames);
[OperationContract(Name = "GetListValuesForRolesAndList")]
List<String> GetListValues(List<String> roleNames, List<String> listNames);
[OperationContract(Name = "GetListValuesForAppUserList")]
List<String> GetListValues(String appName, String userName, List<String> listNames);
[OperationContract]
List<String> GetListsForUser(String userName);
[OperationContract]
bool RoleExists(String roleName);
[OperationContract]
bool ExternalUserExists(String userName, String password);

Answer 1

Each page gets created anew for the request and then discarded - NetTcpBinding is inherently sessionful which means it keeps resources around until the client says they no longer need them or the client goes away for, in your case, 2 hours as you have set the receiveTimeout to 2 hours.
As you don't call Close WCF thinks the session is still alive and so will throttle the requests from the new pages until old sessions start timing out. The .NET 4 default session throttle is fairly high (100 x number of cores) and you have set it yourself at 1000 so you will not see this problem until the processing ahs been running some time. In some ways the default session throttle in .NET 3.5 was better at 10 as it became very obvious very quickly if you were in the situation you are in
I wrote a blog post about sessions a while back