我有一个C＃Lambda函数，该函数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的出处，但我一直在努力找出实际发生的情况。
第一次执行日志：
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
响应：（我知道这不是有效的JSON，我最终要针对的是JSON，但这是我弄清楚后的下一个问题）
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";
}
}
}
因此，代码非常基础，并且使用适用于MySQL和AWS Lambda的MySql.Data 6.10.1-beta Nu-Get软件包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尝试执行时遇到问题。据我了解，Lambda中的状态保存为零。
希望我正在做一些愚蠢的事情或缺少明显的事情，我很乐意收到通知。如果您需要其他信息，请告诉我。
编辑代码：
因此找到了一个修复程序，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，因此由于.net MySQL驱动程序的连接池，虽然我不需要关闭MySQL连接，但实际上我确实需要调用reader.Close();来终止冻结的进程。谢谢你Udo举行了:) 最佳答案
我有点怀疑
该代码看起来像您每次都打开和关闭连接，这很好。但是，您的驱动程序实际上可能不会关闭连接，而只是将其返回到池中。
AWS freezes请求之间的实例。因此，如果池保持与数据库的连接处于打开状态，则由于您的代码被AWS冻结，实际上它可能会断开连接。
查看.net MySQL driver documentation时显示“ 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，但是您应该尝试禁用连接池，添加Pooling=false之类的内容。您可能还想尝试other options。
关于c# - AWS Lambda函数在第一次运行时起作用，但不在第二次运行，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43383752/