Nodejs mysql无法执行查询

我正在使用这个包:https://github.com/mysqljs/mysql

this_obj.pool。getConnection似乎根本无法执行，因为我将console.log放入。

MyLib.prototype.device_table_get_username = function(this_obj, user_id) {
  return new Promise(function (resolve, reject) {
    var sql = "select username from laravel_device where id = " + "'" + user_id + "'";
    console.log();
    console.log("---------");
    console.log(sql);
    // NOTE: ----------- it seems not running at all here. -----------------
    this_obj.pool.getConnection(function(err, connection) {
      console.log("1. no output here");
      connection.query(sql, function(err, rows, fields) {
        console.log("2. no output here");
        connection.release();
        if (err) throw err;
        var msg_obj = {
          rows: rows
        };
        resolve(msg_obj);
      });
    });
  });
}

完整代码

var config = require("../config.js");
var Promise = require('bluebird');
var mysql = require("mysql");
var ON_DEATH = require('death');

// Constructor
function MyLib() {
  // var
  this.db_username = config.db_username;
  this.db_password = config.db_password;
  this.db_name = config.db_name;
  this.db_host = config.db_host;
  this.pool = null;
}

MyLib.prototype.connect_mysql = function() {
    this.pool = mysql.createPool({
        connectionLimit: 400,
        host: this.db_host,
    user: this.db_username,
    password: this.db_password,
    database: this.db_name  
    }); 
}

// close mysql
MyLib.prototype.close_mysql = function() {
    this.pool.end(function (err) {
    // all connections in the pool have ended
    }); 
}

MyLib.prototype.clean_up = function() {
    var this_obj = this;
    ON_DEATH(function(signal, err) {
        console.log();
    console.log("---- script interupted ----");
    console.log("close mysql");
    this_obj.close_mysql();
    });
}

MyLib.prototype.run = function() {
  var this_obj = this;
  this.mqtt_acl_get_rows().then(function(msg_obj){
    var rows = msg_obj.rows;
    // http://stackoverflow.com/questions/28736452/bluebird-promise-serial-iteration-and-resolve-to-modified-array
    this_obj.map_series(this_obj, rows, this_obj.process_mqtt_acl_row).then(function(){
      // finish
      process.exit();
    });

  });
}

MyLib.prototype.device_table_get_username = function(this_obj, user_id) {
  return new Promise(function (resolve, reject) {
    var sql = "select username from laravel_device where id = " + "'" + user_id + "'";
    console.log();
    console.log("---------");
    console.log(sql);
    // NOTE: ----------- it seems not running at all here. -----------------
    this_obj.pool.getConnection(function(err, connection) {
      console.log("1. no output here");
      connection.query(sql, function(err, rows, fields) {
        console.log("2. no output here");
        connection.release();
        if (err) throw err;
        var msg_obj = {
          rows: rows
        };
        resolve(msg_obj);
      });
    });
  });
}

MyLib.prototype.user_table_get_username = function(user_id) {
    var this_obj = this;
  return new Promise(function (resolve, reject) {
    var sql = "select username from laravel_users where id = " + "'" + user_id + "'";
    console.log();
    console.log("---------");
    console.log(sql);
    // NOTE: ----------- it seems not running at all here. -----------------
    this_obj.pool.getConnection(function(err, connection) {
      connection.query(sql, function(err, rows, fields) {
        connection.release();
        if (err) throw err;
        var msg_obj = {
          rows: rows
        };
        resolve(msg_obj);
      });
    });
  });
}

MyLib.prototype.process_mqtt_acl_row = function(this_obj, value, index, length) {
    var row_id = value.id;
  var user_id = value.user_id;
  var mqtt_user_type_id = value.mqtt_user_type_id;
  var is_device = 2;
  var is_human = 1;
  if(mqtt_user_type_id == is_device) {
    console.log("-device-");
        this_obj.device_table_get_username(this_obj, user_id).then(function(msg_obj){      
            var rows = msg_obj.rows;
      console.log(msg_obj);
        });
  }
  else if(mqtt_user_type_id == is_human) {
    console.log("-human-");
        this_obj.user_table_get_username(user_id).then(function(msg_obj){
            var rows = msg_obj.rows;
      console.log(msg_obj);
        });
  }
  else {
    console.log("process_mqtt_acl_row, not calling");
  }
  return value;
}

// http://stackoverflow.com/questions/28736452/bluebird-promise-serial-iteration-and-resolve-to-modified-array
MyLib.prototype.map_series = function(this_obj, things, fn) {
  var results = [];
  return Promise.each(things, function(value, index, length) {
    // value
    // value == { id: 303, user_id: 4, mqtt_user_type_id: 1 }
    // call fn
    var ret = fn(this_obj, value, index, length);
    // push result
    results.push(ret);
    return ret;
  });
}

MyLib.prototype.mqtt_acl_get_rows = function() {
    var this_obj = this;
    return new Promise(function (resolve, reject) {
        var sql = "select id, user_id, mqtt_user_type_id from laravel_mqtt_acl order by id asc";
    console.log();
    console.log("---------");
    console.log(sql);
    // NOTE: this one is working
        this_obj.pool.getConnection(function(err, connection) {
      connection.query(sql, function(err, rows, fields) {
        connection.release();
        if (err) throw err;
        var msg_obj = {
          rows: rows
        };
        resolve(msg_obj); 
      });
    });
    });
}

module.exports = MyLib;

更新1 我把它从connectionLimit: 400变成了connectionLimit: 4。它似乎能够连接。我将做更多的测试