Question

我正在尝试使用node mysql library重现我在EC2上的node.js应用中看到的MySQL错误：

连接丢失：服务器关闭了连接。

我无法在本地重现错误 - 我的代码处理数据库的处理很好 - 它只需每隔几秒重新检查一次，并在重新启动后重新连接到数据库。在EC2上，它发生在太平洋时间凌晨4点左右，但数据库仍然运行良好。

我想

使用我的本地mysql重现崩溃
在我的mysql帮助程序模块中添加我需要的任何逻辑来处理此

这是我的node.js app中的错误：

2012-10-22T08：45：40.518Z - 错误：uncaughtException date = Mon 10月22日 2012 08:45:40 GMT + 0000（UTC），pid = 14184，uid = 0，gid = 0， cwd = / home / ec2-user / my-app，execPath = / usr / bin / nodejs， version = v0.6.18，argv = [/ usr / local / bin / node， /home/ec2-user/my-app/app.js,-my-app]，rss = 15310848， heapTotal = 6311392，heapUsed = 5123292，loadavg = [0.0029296875， 0.0146484375,0.04541015625]，正常运行时间= 3238343.511107486，trace = [column = 13，文件= /家庭/ EC2用户/我的应用程序内/ node_modules / MySQL的/ lib目录/协议/ Protocol.js， function = Protocol.end，line = 63，method = end，native = false，column = 10， file = stream.js，function = Socket.onend，line = 80，method = onend， native = false，column = 20，file = events.js，function = Socket.emit， line = 88，method = emit，native = false，column = 51，file = net.js， function = TCP.onread，line = 388，method = onread，native = false]， stack = [错误：连接丢失：服务器关闭连接。，在Protocol.end （/home/ec2-user/my-app/node_modules/mysql/lib/protocol/Protocol.js:63:13），在Socket.onend（stream.js：80：10），在Socket.emit （events.js:88:20），在TCP.onread（net.js：388：51）]

这是我的代码（mysql helper module）：

module.exports = function (conf,logger) {
  var mysql = require('mysql');

  var connectionState = false;
  var connection = mysql.createConnection({
    host: conf.db.hostname,
    user: conf.db.user,
    password: conf.db.pass,
    database: conf.db.schema,
    insecureAuth: true
  });

  function attemptConnection(connection) {
    if(!connectionState){
      connection = mysql.createConnection(connection.config);
      connection.connect(function (err) {
        // connected! (unless `err` is set)
        if (err) {
          logger.error('mysql db unable to connect: ' + err);
          connectionState = false;
        } else {
          logger.info('mysql connect!');
          connectionState = true;
        }
      });
      connection.on('close', function (err) {
        logger.error('mysqldb conn close');
        connectionState = false;
      });
      connection.on('error', function (err) {
        logger.error('mysqldb error: ' + err);
        connectionState = false;

        /*
        if (!err.fatal) {
          return;
        }
        if (err.code !== 'PROTOCOL_CONNECTION_LOST') {
          throw err;
        }
        */
      });
    }
  }
  attemptConnection(connection);

  var dbConnChecker = setInterval(function(){
    if(!connectionState){
      logger.info('not connected, attempting reconnect');
      attemptConnection(connection);
    }
  }, conf.db.checkInterval);

  return connection;
};

Answer 1

查看node-mysql

中的mysql池功能

var mysql = require('mysql');
var pool  = mysql.createPool({
  host     : 'example.org',
  user     : 'bob',
  password : 'secret'
});

pool.getConnection(function(err, connection) {
  // connected! (unless `err` is set)
  connection.end();
});

Answer 2

我遇到了类似的问题，并创建了一个getConnection（）包装函数，该函数在将mysql连接返回给调用者之前检查mysql连接的运行状况，并根据需要重新建立连接。在我的测试中，它已经为应用程序透明地处理了致命和非致命的连接问题。如果连接只是超时，则应用程序将恢复，而不会出现任何错误。如果存在暂时但致命的数据库连接问题，则只要数据库连接可用，应用程序就会自动恢复运行。

就复制测试问题而言，将以下两行添加到[mysqld]块下的my.ini或my.cnf文件中：

interactive_timeout=30
wait_timeout=30

以下是我命名为“database.js”的文件的内容：

var mysql = require("mysql");
var CONFIG = require(__dirname + "/configuration");

module.exports.getConnection = function() {
    // Test connection health before returning it to caller.
    if ((module.exports.connection) && (module.exports.connection._socket)
            && (module.exports.connection._socket.readable)
            && (module.exports.connection._socket.writable)) {
        return module.exports.connection;
    }
    console.log(((module.exports.connection) ?
            "UNHEALTHY SQL CONNECTION; RE" : "") + "CONNECTING TO SQL.");
    var connection = mysql.createConnection({
        host     : CONFIG.db.host,
        user     : CONFIG.db.user,
        password : CONFIG.db.password,
        database : CONFIG.db.database,
        port     : CONFIG.db.port
    });
    connection.connect(function(err) {
        if (err) {
            console.log("SQL CONNECT ERROR: " + err);
        } else {
            console.log("SQL CONNECT SUCCESSFUL.");
        }
    });
    connection.on("close", function (err) {
        console.log("SQL CONNECTION CLOSED.");
    });
    connection.on("error", function (err) {
        console.log("SQL CONNECTION ERROR: " + err);
    });
    module.exports.connection = connection;
    return module.exports.connection;
}

// Open a connection automatically at app startup.
module.exports.getConnection();

// If you've saved this file as database.js, then get and use the
// connection as in the following example:
// var database = require(__dirname + "/database");
// var connection = database.getConnection();
// connection.query(query, function(err, results) { ....

Answer 3

这是我最终使用的内容，而且效果非常好。偶尔连接丢失/重启它恢复得很好。我有一个database.js文件，它建立连接并定期检查它们。

提出要求：

var conn = require('./database');
var sql = 'SELECT foo FROM bar;';
conn.query(sql, [userId, plugId], function (err, rows) {
   // logic
}

这是我的databbase.js

var mysql = require('mysql');
var Common = require('./common');
var conf = Common.conf;
var logger = Common.logger;

var connectionState = false;
var connection = mysql.createConnection({
  host: conf.db.hostname,
  user: conf.db.user,
  password: conf.db.pass,
  database: conf.db.schema,
  insecureAuth: true
});
connection.on('close', function (err) {
  logger.error('mysqldb conn close');
  connectionState = false;
});
connection.on('error', function (err) {
  logger.error('mysqldb error: ' + err);
  connectionState = false;
});

function attemptConnection(connection) {
  if(!connectionState){
    connection = mysql.createConnection(connection.config);
    connection.connect(function (err) {
      // connected! (unless `err` is set)
      if (err) {
        logger.error('mysql db unable to connect: ' + err);
        connectionState = false;
      } else {
        logger.info('mysql connect!');

        connectionState = true;
      }
    });
    connection.on('close', function (err) {
      logger.error('mysqldb conn close');
      connectionState = false;
    });
    connection.on('error', function (err) {
      logger.error('mysqldb error: ' + err);

      if (!err.fatal) {
        //throw err;
      }
      if (err.code !== 'PROTOCOL_CONNECTION_LOST') {
        //throw err;
      } else {
        connectionState = false;
      }

    });
  }
}
attemptConnection(connection);

var dbConnChecker = setInterval(function(){
  if(!connectionState){
    logger.info('not connected, attempting reconnect');
    attemptConnection(connection);
  }
}, conf.db.checkInterval);

// Mysql query wrapper. Gives us timeout and db conn refreshal! 
var queryTimeout = conf.db.queryTimeout;
var query = function(sql,params,callback){
  if(connectionState) {
    // 1. Set timeout
    var timedOut = false;
    var timeout = setTimeout(function () {
      timedOut = true;
      callback('MySQL timeout', null);
    }, queryTimeout);

    // 2. Make query
    connection.query(sql, params, function (err, rows) {
      clearTimeout(timeout);
      if(!timedOut) callback(err,rows);
    });
  } else {
    // 3. Fail if no mysql conn (obviously)
    callback('MySQL not connected', null);
  }
}

// And we present the same interface as the node-mysql library!
// NOTE: The escape may be a trickier for other libraries to emulate because it looks synchronous
exports.query = query;
exports.escape = connection.escape;

Answer 4

使用generic-pool，我写了一些在本地工作的东西。我想我会测试它，看看它是否在服务器端以奇怪的方式崩溃。

// Test node connection pool stuff

// Create a MySQL connection pool with
// a max of 10 connections, a min of 2, and a 30 second max idle time
var poolModule = require('generic-pool');
var pool = poolModule.Pool({
    name     : 'mysql',
    create   : function(callback) {
        var Client = require('mysql').Client; // use node-mysql library in all it's dubious glory
        var c = new Client();
        c.user     = 'root';
        c.password = 'xxx';
        c.database = 'test';
        c.on('close', function (err) {
          console.log('mysqldb conn close');
        });
        c.on('error', function (err) {
          console.log('mysqldb error: ' + err);
        });

        // parameter order: err, resource
        // new in 1.0.6
        callback(null, c);
    },
    destroy  : function(client) { client.end(); },
    max      : 10,
    // optional. if you set this, make sure to drain() (see step 3)
    min      : 2, 
    // specifies how long a resource can stay idle in pool before being removed
    idleTimeoutMillis : 30000,
     // if true, logs via console.log - can also be a function
    log : true 
});

var http = require('http');
http.createServer(function (req, res) {

  // Get db conn
  pool.acquire(function(err, client) {
      if (err) {
          // handle error - this is generally the err from your
          // factory.create function 
          console.log('pool.acquire err: ' + err);
          res.writeHead(500, {'Content-Type': 'application/json'});
          out = {
            err: err
          }
          res.end(JSON.stringify(out));
      }
      else {
          client.query("select * from foo", [], function(err, results) {

              if(err){
                res.writeHead(500, {'Content-Type': 'application/json'});
                out = {
                  err: err
                }
                res.end(JSON.stringify(out));
              } else {
                res.writeHead(500, {'Content-Type': 'application/json'});
                out = {
                  results: results
                }
                res.end(JSON.stringify(out));
              }


              // return object back to pool
              pool.release(client);
          });
      }
  });
}).listen(9615);

相当请不要在凌晨4点死亡，没有明显的理由！

Answer 5

解决方案是使用池连接！

你可以编写代码来手动处理连接，它可以工作。但是池是为此设计的，使用池连接解决了连接丢弃错误。

var mysql = require('mysql');
var pool  = mysql.createPool({
    connectionLimit : 10,
     host            : 'example.org',
    user            : 'bob',
     password        : 'secret',
      database        : 'my_db'
    });

   pool.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
            if (error) throw error;
            console.log('The solution is: ', results[0].solution);
         });

pooling mysql connection

重现MySQL错误：服务器关闭连接（node.js）

5 个答案: