为什么node.js有个查询慢的连接会拖慢查询快的连接？
index.js
var http = require('http');
var url = require('url');
var fs = require('fs');
var DBHelper = require('./dbHelper');
http.createServer(function (request, response) {
var pathname = url.parse(request.url).pathname;
if (pathname == '/') {
fs.readFile(__dirname + '/index.html', function (err, data) {
if (err) {
console.log(err);
// HTTP 状态码: 404 : NOT FOUND
// Content Type: text/plain
response.writeHead(404, { 'Content-Type': 'text/html' });
} else {
// HTTP 状态码: 200 : OK
// Content Type: text/plain
response.writeHead(200, { 'Content-Type': 'text/html' });
// 响应文件内容
response.write(data.toString());
}
// 发送响应数据
response.end();
});
}
else if (pathname == '/jquery-3.1.0.js') {
fs.readFile(__dirname + '/jquery-3.1.0.js', function (err, data) {
if (err) {
console.log(err);
// HTTP 状态码: 404 : NOT FOUND
// Content Type: text/plain
response.writeHead(404, { 'Content-Type': 'text/html' });
} else {
// HTTP 状态码: 200 : OK
// Content Type: text/plain
response.writeHead(200, { 'Content-Type': 'application/javascript' });
// 响应文件内容
response.write(data.toString());
}
// 发送响应数据
response.end();
});
}
else if(pathname=='/oo') {
try {
var dbHelper = new DBHelper();
(async () => {
console.time(pathname+'_2')
let data = await dbHelper.query(`declare @i int
set @i=1
while @i<10000
begin
select top 2 * from tUser with(nolock)
set @i=@i+1
end`,pathname); //这里模拟查询慢的连接
response.writeHead(200, { 'Content-Type': 'application/json' });
response.end(JSON.stringify(data));
console.timeEnd(pathname+'_2')
})()
}
catch (e) {
console.error(e)
}
}
else {
try {
var dbHelper = new DBHelper();
(async () => {
console.time(pathname+'_1')
let data = await dbHelper.query('select top 2 * from tDept with(nolock)',pathname);
response.writeHead(200, { 'Content-Type': 'application/json' });
response.end(JSON.stringify(data));
console.timeEnd(pathname+'_1')
})()
}
catch (e) {
console.error(e)
}
}
}).listen(8888);
dbHelper.js
const Connection = require('tedious').Connection;
const Request = require('tedious').Request;
const config = {
userName: 'sa', // update me
password: '', // update me
server: '',
options: {
port: '5555',
database: '',
rowCollectionOnRequestCompletion: true
}
}
class DBHelper {
constructor() {
this.connection = new Connection(config);
}
async query(cmd,url) {
var p = this;
var promise = new Promise((resolve, reject) => {
p.connection.on('connect', function (err) {
if (err) {
reject(err);
}
else {
let request = new Request(cmd, function (err, rowCount, rows) {
if (err) {
reject(err);
}
else {
resolve(rows);
}
p.connection.close();
})
p.connection.execSql(request);
}
})
})
var data = {
Data: null,
IsSuccess: true,
Msgs: []
}
try {
console.time(url)
var rs = await promise;
console.timeEnd(url)
data.Data=[];
//console.time(url+'data')
rs.forEach(function(arr){
var _obj={ };
arr.forEach(function(obj){
_obj[obj.metadata.colName]=obj.value;
});
data.Data.push(_obj);
})
//console.timeEnd(url+'data')
return data;
}
catch (e) {
data.IsSuccess = false;
data.Msgs.push(e);
return data;
}
}
_query(cmd) {
var p = this;
return new Promise((resolve, reject) => {
p.connection.on('connect', function (err) {
if (err) {
reject(err);
}
else {
let request = new Request(cmd, function (err, rowCount, rows) {
if (err) {
reject(err);
}
else {
resolve(rows);
}
p.connection.close();
})
p.connection.execSql(request);
}
})
})
}
}
module.exports = DBHelper;
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<script src="./jquery-3.1.0.js"></script>
<title>Document</title>
</head>
<body>
<button id="btn1">click me</button>
<button id="btn2">click me</button>
<script>
var ajax = new XMLHttpRequest();
var btn1 = document.getElementById('btn1');
var btn2 = document.getElementById('btn2');
var i=1,j=1;
btn1.addEventListener('click', function () {
/*ajax.open('Get', 'ooo', true);
ajax.onreadystatechange=processResponse;
ajax.send();*/
$.ajax({
type: 'Get',
url: 'ooo'+i+'_'+Math.random(),
dataType: 'json',
success: function (data) {
console.log(data)
},
});
i++
})
btn2.addEventListener('click', function () {
/*ajax.open('Get', 'ooo', true);
ajax.onreadystatechange=processResponse;
ajax.send();*/
$.ajax({
type: 'Get',
url: 'oo',
dataType: 'json',
success: function (data) {
console.log(data)
},
});
})
function processResponse() {
//响应完成且响应正常
if (ajax.readyState == 1) {
console.log("XMLHttpRequest对象开始发送请求");
console.log('--------------------------------------------------------------');
} else if (ajax.readyState == 2) {
console.log("XMLHttpRequest对象的请求发送完成");
console.log('--------------------------------------------------------------');
} else if (ajax.readyState == 3) {
console.log("XMLHttpRequest对象开始读取服务器的响应");
console.log('--------------------------------------------------------------');
} else if (ajax.readyState == 4) {
console.log("XMLHttpRequest对象读取服务器响应结束");
console.log('--------------------------------------------------------------');
if (ajax.status == 200) {
//信息已经成功返回，开始处理信息
//先捕获下所有的请求头
var headers = ajax.getAllResponseHeaders();
console.log(headers);
console.log('--------------------------------------------------------------');
//得到服务器返回的信息
var infor = ajax.responseText;
console.log(infor);
} else {
alert("所请求的服务器端出了问题");
}
}
}
</script>
</body>
</html>
结果：
这只是查询不同表的情况，如果是查询同一张表的情况，在chrome下可以看到在stalled状态下等待很久，求解? 数据库是sql server 2008r2,连接模块是tedious
