【发布时间】：2017-09-09 01:45:43
【问题描述】：
我有一个 C# Lambda 函数，它在第一次执行时有效，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，但我很难弄清楚实际发生了什么。
第一个执行日志：
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
响应：（我知道这不是有效的 JSON，这是我最终的目标，但一旦我弄清楚了，这将是我处理的下一个项目）
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";
}
}
}
所以代码非常基本，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。
我不明白为什么在第一次尝试而不是第二次执行时会出现问题。据我了解，Lambda 中的状态保存为零。
希望我在做一些愚蠢的事情或遗漏了一些显而易见的事情，我很乐意收到通知。如果您需要更多信息，请告诉我。
编辑代码：
所以找到了一个修复，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，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，但实际上我确实需要调用 reader.Close(); 来终止冻结过程。谢谢你 Udo 举行:)
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标签： c# mysql amazon-web-services aws-lambda