Question

我们有一个表，其中的列之一为 text 数据类型，并且只有3条记录。我们使用ExecuteNonQuery（）在文本列上执行更新查询，并引发错误“从流中读取时发生异常”。错误是随机发生的，这意味着有时会执行查询，有时会抛出错误，但是最大比率是错误的，就像它在10中抛出9次错误一样。我们正在使用Npgsql -Version 4.0.4和PostgreSQL version 11.1 windows 2012 R2。另外，我们尝试将超时设置为0，但是会立即引发错误，因此它也与超时错误无关。以下是我们的例外。

   at Npgsql.NpgsqlReadBuffer.<>c__DisplayClass31_0.<g__EnsureLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnector.<>c__DisplayClass161_0.<g__ReadMessageLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlDataReader.d__46.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlDataReader.NextResult()
   at Npgsql.NpgsqlCommand.d__100.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
   at Npgsql.NpgsqlCommand.ExecuteReader()
   at Npgsql.PostgresDatabaseInfo.d__13.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.PostgresDatabaseInfo.d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.PostgresDatabaseInfoFactory.d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlDatabaseInfo.d__79.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnector.d__150.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnector.d__149.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.ConnectorPool.d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnection.<>c__DisplayClass32_0.<g__OpenLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlConnection.Open()
   at DataAccessLayer.Providers.Executors.PostgreSQL.ExecuteQuery(PreparedStatement`1 preparedStatement, Int32 timeout) in C:\code\Framework\DataAccessLayer\Providers\Executors\PostgreSQL.cs:line 64
   at DataAccessLayer.Providers.PostgreSQL.ExecuteQuery(IExecuteQuerySupport command, Int32 timeout) in C:\main\code\Framework\DataAccessLayer\Providers\Modules\PostgreSQLServer.cs:line 26
   at BAL.Base.RolesManagement.Roles.GetDatabaseRole(Int64 userID) in C:\main\code\BusinessAccessLayer\BAL\Base\RolesManagement\Roles.cs:line 398
   at API.Controllers.MyWorkspacesController.ConnectGroup(Int64 groupID) in C:\main\code\Web\API\Controllers\MyWorkspacesController.cs:line 390
   --- End of exception stack trace ---
    Message : Unable to read data from the transport connection: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
StackTrace :    at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
   at Npgsql.NpgsqlReadBuffer.<>c__DisplayClass31_0.<g__EnsureLong|0>d.MoveNext()
    --- End of inner exception stack trace --- 
    Message : A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
StackTrace :    at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
   --- End of inner exception stack trace ---

Answer 1

我遇到了同样的错误，因为我的服务器安装的 PostgreSQL 是满 CPU。有一些查询执行多次无法释放，所以它使我的服务器已满。

如果您的服务器已满，您可以参考 this 文章以查看解决方案。
如果不是，则可能需要在连接到数据库时增加最大池和连接超时。

从npgsql中的流读取时发生异常

1 个答案: