我有一个C＃Lambda函数可以在第一次执行时运行但在第二次执行时失败。 我创建了一些日志来帮助我解决问题所在，但我正在努力弄清楚实际发生了什么。
首次执行日志：
START RequestId: XXXXXXXXXXXXXXXXXXXXXXXXXXXXX Version: $LATEST
1. Connecion to Database is Open
2. Running Query: SELECT * FROM Employee3
3. Returning Results
4. Close connection
5. Close reader
6. Dispose cmd
7. Configure encoding and string to stream
END RequestId: XXXXXXXXXXXXXXXXXXXXXXXX
REPORT RequestId: XXXXXXXXXXXXXXXXXXXXXXXX Duration: 10097.73 ms Billed Duration: 10100 ms Memory Size: 128 MB Max Memory Used: 41 MB
回复：（我知道这不是有效的JSON，我最终的目标是，但这将是我解决的下一个项目）
Connecion to Database is Open
Joe
Bob
Mary
第二次执行日志：
START RequestId: XXXXXXXXXXXXXXXXXXXXXXXXXXXXX Version: $LATEST
1. Connecion to Database is Open
2. Running Query: SELECT * FROM Employee3
Connection must be valid and open.: InvalidOperationException
at MySql.Data.MySqlClient.MySqlCommand.Throw(Exception ex)
at MySql.Data.MySqlClient.MySqlCommand.CheckState()
at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
at LambdaDBTest.Function.returnRows(MySqlConnection connection)
at LambdaDBTest.Function.FunctionHandler(Stream input, ILambdaContext context)
at lambda_method(Closure , Stream , Stream , ContextInfo )
END RequestId: XXXXXXXXXXXXXXXXXXXXXXXX
REPORT RequestId: XXXXXXXXXXXXXXXXXXXXXXXX Duration: 1203.12 ms Billed Duration: 1300 ms Memory Size: 128 MB Max Memory Used: 47 MB
以下是我正在使用的代码：
using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;
using Amazon.Lambda.Core;
using Amazon.Lambda.Serialization;
using System.Text;
// Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
[assembly: LambdaSerializerAttribute(typeof(Amazon.Lambda.Serialization.Json.JsonSerializer))]
namespace LambdaDBTest
{
public class Function
{
/// <summary>
/// A simple function that takes a string and does a ToUpper
/// </summary>
/// <param name="input"></param>
/// <param name="context"></param>
/// <returns></returns>
public Stream FunctionHandler(Stream input, ILambdaContext context)
{
var dbCon = DBConnection.Instance();
dbCon.Server = "AWS-URI";
dbCon.DatabaseName = "DBNAME";
dbCon.User = "DBUSER";
dbCon.Password = "DBPASS";
string textInput;
if (dbCon.IsConnect())
{
textInput = "Connecion to Database is Open";
LambdaLogger.Log("\n 1. " + textInput);
textInput += returnRows(dbCon.Connection);
}
else
{
textInput = "\n Connecion to Database is NOT Open";
}
dbCon.Close();
LambdaLogger.Log("\n 7. Configure encoding and string to stream\n");
input = new System.IO.MemoryStream(System.Text.Encoding.UTF8.GetBytes(textInput));
return input;
}
public static MemoryStream GenerateStreamFromString(string value)
{
return new MemoryStream(Encoding.UTF8.GetBytes(value ?? ""));
}
static string returnRows(MySqlConnection connection)
{
string output = null;
string query = @"SELECT * FROM Employee3";
LambdaLogger.Log("\n 2. Running Query: " + query);
var cmd = new MySqlCommand(query, connection);
var reader = cmd.ExecuteReader();
LambdaLogger.Log("\n 3. Returning Results");
while (reader.Read())
{
output += "\n" + (string)reader["Name"];
}
LambdaLogger.Log("\n 4. Close connection");
connection.Close();
LambdaLogger.Log("\n 5. Close reader");
reader.Close();
LambdaLogger.Log("\n 6. Dispose cmd");
cmd.Dispose();
return output + "\r";
}
}
}
所以代码是非常基础的，并且使用MySql.Data 6.10.1-beta Nu-Get Package for MySQL和AWS Lambda进行了一些剪切和粘贴工作。
我无法理解为什么我在第一次尝试而不是第二次尝试时遇到问题。据我所知，Lambda中没有状态保存。
希望我做一些愚蠢的事情或遗漏一些明显的事情，我很乐意收到通知。如果您需要其他信息，请与我们联系。
已编辑代码：
所以发现修复程序如下所示：
public Stream FunctionHandler(Stream input, ILambdaContext context)
{
var dbCon = DBConnection.Instance();
dbCon.Server = "######.rds.amazonaws.com";
dbCon.DatabaseName = "#####";
dbCon.User = "#####";
dbCon.Password = "######";
string textInput;
if (dbCon.IsConnect())
{
textInput = "Connecion to Database is Open";
LambdaLogger.Log("\n 1. " + textInput);
textInput += returnRows(dbCon.Connection);
}
else
{
textInput = "\n Connecion to Database is NOT Open";
}
// LambdaLogger.Log("\n 7. Close Database connection");
//dbCon.Close();
LambdaLogger.Log("\n 8. Configure encoding and string to stream\n");
input = new System.IO.MemoryStream(System.Text.Encoding.UTF8.GetBytes(textInput));
return input;
}
public static MemoryStream GenerateStreamFromString(string value)
{
return new MemoryStream(Encoding.UTF8.GetBytes(value ?? ""));
}
static string returnRows(MySqlConnection connection)
{
string output = null;
string query = @"SELECT * FROM Employee3";
LambdaLogger.Log("\n 2. Running Query: " + query);
var cmd = new MySqlCommand(query, connection);
var reader = cmd.ExecuteReader();
LambdaLogger.Log("\n 3. Returning Results");
while (reader.Read())
{
output += "\n" + (string)reader["Name"];
}
// LambdaLogger.Log("\n 4. Close connection");
//connection.Close();
LambdaLogger.Log("\n 5. Close reader");
reader.Close();
// LambdaLogger.Log("\n 6. Dispose cmd");
//cmd.Dispose();
return output + "\r";
}
进程reader被Lambda冻结了，所以虽然由于.net MySQL驱动程序的连接池我不需要关闭MySQL连接，但我确实需要调用reader.Close();杀死冷冻过程。谢谢Udo Held：）
答案 0 :(得分：2)
我有一种怀疑。 代码看起来像每次打开和关闭连接都很好。但是，您的驱动程序可能实际上并未关闭连接，而只是将其返回到池中。 AWS freezes请求之间的实例。因此，如果池中的数据库连接保持打开状态，那么由于您的代码被AWS冻结，它实际上可能会断开连接。
查看.net MySQL driver documentation状态“The Connector/Net supports connection pooling for better performance and scalability with database-intensive applications. This is enabled by default.”
您没有提供连接字符串，但您应该尝试禁用添加Pooling=false之类的连接池。您可能还想尝试other options。