NodeJS express 服务器卡在 AsyncJS 系列答案

【问题标题】：NodeJS express server stuck at AsyncJS seriesNodeJS express 服务器卡在 AsyncJS 系列
【发布时间】：2017-06-21 16:05:12
【问题描述】：

路线代码

router.post('/add', function(req, res) {
    const compulsoryFields = ['primary_id', 'secondary_id', 'assessment_note_id', 'packing_list_id', 'model_id']

    for(var i = 0; i < compulsoryFields.length; i++) {
        if(req.body[compulsoryFields[i]] == '') {
            req.flash('warning_msg', 'Please make sure all * fields are supplied')
            res.redirect('/rmv/add')
            return
        }
    }

    async.series([
        function(callback) {
            Vehicle.existsByPrimaryId(req.body.primary_id, callback)
        }, function(callback) {
            Vehicle.existsBySecondaryId(req.body.secondary_id, callback)
        }
    ], function(err, details) {
        if(!details[0]) {
            if(!details[1]) {

                var vehicle = { id: null }

                for(var key in req.body) {
                    vehicle[key] = req.body[key]
                }

                async.series([
                    function(callback) {
                        Vehicle.add(vehicle, callback)
                    }
                ], function(err, details_l2) {
                    if(details_l2[0]) {
                        req.flash('warning_msg', 'Vehicle added successfully')
                        res.redirect('/rmv/add')
                    } else {
                        req.flash('warning_msg', 'Error occured while adding vehicle. Please try again')
                        res.redirect('/rmv/add')
                    }
                })

            } else {
                req.flash('warning_msg', 'Chassis/Frame number already exists')
                res.redirect('/rmv/add')
            }
        } else {
            req.flash('warning_msg', 'Engine/Motor number already exists')
            res.redirect('/rmv/add')
        }
    })
})

型号代码

const MySql = require('../comms/rmv_mysql_con')
const Vehicle = module.exports = {}

Vehicle.add = function(vehicle, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('INSERT INTO vehicle SET ?', vehicle, function(err, result) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, true)
        })
    })
}

Vehicle.getCount = function(callback) {
    MySql.pool.getConnection(function(pool_err, connection) {
        connection.query('SELECT COUNT(*) AS \'vehicle_count\' FROM vehicle', function(err, rows) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, rows[0]['vehicle_count'])
        })
    })
}

Vehicle.search = function(skw, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('SELECT vehicle.*, primary_name, secondary_name, name FROM vehicle, model WHERE vehicle.model_id = model.id AND CONCAT(model_id, packing_list_id, assessment_note_id, primary_id, secondary_id, sale_date, customer_first_name, customer_last_name, customer_phone_number, customer_address_no, customer_address_street, customer_address_district, customer_nic, rmv_documents_received_date, rmv_documents_sent_date, cr_received_date, plate_number, plate_sent_date, cr_sent_date, remarks) LIKE \'%' + skw + '%\'', function(err, rows, fields) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, rows)
        })
    })
}

Vehicle.existsByPrimaryId = function(id, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('SELECT * FROM vehicle WHERE primary_id = ?', id, function(err, rows, fields) {
            connection.release()
            if(rows.length > 0) {
                return callback(err, true)
            }
            callback(err, false)
        })
    })
}

Vehicle.getAll = function(callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('SELECT vehicle.*, primary_name, secondary_name, name FROM vehicle, model WHERE vehicle.model_id = model.id', function(err, rows, fields) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, rows)
        })
    })
}

Vehicle.updateById = function(vehicle, id, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('UPDATE vehicle SET ? WHERE id = ?', [vehicle, id], function(err, result) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, true)
        })
    })
}

Vehicle.getVehicleById = function(id, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('SELECT  vehicle.id, primary_id, sale_date, customer_first_name, customer_last_name, customer_phone_number, customer_address_no, customer_address_street, customer_address_district, customer_nic, rmv_documents_received_date, rmv_documents_sent_date, cr_received_date, plate_number, plate_sent_date, cr_sent_date, remarks, primary_name, secondary_name FROM vehicle, model WHERE vehicle.model_id = model.id AND vehicle.id = ?', id, function(err, rows, fields) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, rows)
        })
    })
}

Vehicle.existsBySecondaryId = function(id, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('SELECT * FROM vehicle WHERE secondary_id = ?', id, function(err, rows, fields) {
            connection.release()
            if(rows.length > 0) {
                return callback(err, true)
            }
            callback(err, false)
        })
    })

问题是，当添加 5-10 个请求后，服务器挂起快速调试的输出如下

/rmv/add
  express:router router  : /rmv/add +0ms
  express:router dispatching POST /rmv/add +0ms
  express:router trim prefix (/rmv) from url /rmv/add +0ms
  express:router router /rmv : /rmv/add +0ms
  express:router dispatching POST /add +0ms
  express:router <anonymous>  : /rmv/add +0ms
  express:router <anonymous>  : /rmv/add +1ms
  express:router <anonymous>  : /rmv/add +0ms
  express:router dispatching GET /rmv/add +134ms
  express:router query  : /rmv/add +0ms
  express:router expressInit  : /rmv/add +0ms
  express:router jsonParser  : /rmv/add +0ms
  express:router urlencodedParser  : /rmv/add +0ms
  express:router cookieParser  : /rmv/add +0ms
  express:router serveStatic  : /rmv/add +0ms
  express:router session  : /rmv/add +4ms
  express:router initialize  : /rmv/add +0ms
  express:router authenticate  : /rmv/add +0ms
  express:router <anonymous>  : /rmv/add +4ms
  express:router <anonymous>  : /rmv/add +0ms
/rmv/add
  express:router router  : /rmv/add +1ms
  express:router dispatching GET /rmv/add +0ms
  express:router trim prefix (/rmv) from url /rmv/add +0ms
  express:router router /rmv : /rmv/add +0ms
  express:router dispatching GET /add +0ms
  express:router <anonymous>  : /rmv/add +0ms
  express:router <anonymous>  : /rmv/add +0ms
  express:router <anonymous>  : /rmv/add +0ms

当服务器挂起时，我发出的每个请求都会卡住，除了那些不使用 asyncjs 的请求。服务器工作正常，当它重新启动时，在收到 5-10 个添加发布路由的请求后问题再次出现。

【问题讨论】：

标签： javascript node.js express server

【解决方案1】：

不知道它是否来自这里，但在您的 Vehicle 模型的方法中，如果您尝试连接池时 Mysql 返回错误，您还应该返回回调。

也许记录这些错误以测试错误是否来自这里。因为如果一个回调没有被解析，那么你就无法访问 async.series 方法的最终函数。

async.series([
   function(callback) {
      Vehicle.existsByPrimaryId(req.body.primary_id, callback)
   }, function(callback) {
      Vehicle.existsBySecondaryId(req.body.secondary_id, callback)
   }
], function() {
   // can't access this if there is a pool error with 
   // vehicle.existsByPrimaryId or Vehicle.existsBySecondaryId,
   // since callback is not resolved
});

之前：

Vehicle.updateById = function(vehicle, id, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        connection.query('UPDATE vehicle SET ? WHERE id = ?', [vehicle, id], function(err, result) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, true)
        })
    })
}

之后：

Vehicle.updateById = function(vehicle, id, callback) {
    MySql.pool.getConnection(function(pool_err, connection){
        if (poll_err) {
           return callback(poll_err, false);
        }
        connection.query('UPDATE vehicle SET ? WHERE id = ?', [vehicle, id], function(err, result) {
            connection.release()
            if(err) {
                return callback(err, false)
            }
            callback(err, true)
        })
    })
}

【讨论】：