当通过ASP.NET成员资格检查用户角色时,SemaphoreFullException

我有一个页面，在执行一些任务之前检查用户是否处于特定的角色，并且对功能没有问题，并且没有对相关代码进行明显的相关更改。该站点在我的开发计算机(Windows Vista)上运行IIS 7.0，数据库是MS SQL 2005在单独的服务器上。突然，对User.IsInRole的所有调用都会导致

System.Threading.SemaphoreFullException: Adding the specified count to the semaphore would cause it to exceed its maximum count.

我确定重新启动IIS将“解决”的问题，但我想了解是什么原因，所以我可以确保它不会发生在我的生产网站。

堆栈跟踪的顶部是：

[SemaphoreFullException: Adding the specified count to the semaphore would cause it to exceed its maximum count.]
System.Threading.Semaphore.Release(Int32 releaseCount) +6065293
System.Data.ProviderBase.DbConnectionPool.PutNewObject(DbConnectionInternal obj) +57
System.Data.ProviderBase.DbConnectionPool.DeactivateObject(DbConnectionInternal obj) +338
System.Data.ProviderBase.DbConnectionPool.PutObject(DbConnectionInternal obj,Object owningObject) +163
System.Data.ProviderBase.DbConnectionInternal.CloseConnection(DbConnection owningObject,DbConnectionFactory connectionFactory) +117
System.Data.SqlClient.SqlInternalConnection.CloseConnection(DbConnection owningObject,DbConnectionFactory connectionFactory) +37
System.Data.SqlClient.SqlConnection.Close() +158
System.Web.DataAccess.SqlConnectionHolder.Close() +25
System.Web.Security.SqlRoleProvider.GetRolesForUser(String username) +847
System.Web.Security.RolePrincipal.IsInRole(String role) +182