Hi,
I' am a little bit confused. Why do you wrap a Promise into Promises?
It does not make sense, because Promises themselves check if the
returned value is a promise, so the promise pipeline does what you do
internally. There is no need of try/catch, if you do no error handling.
The Promise mechanics wraps your function into a try/catch block. Do
only the transformation in the fullfill function and catch the error in
an reject function and handle it there.
var resolver = function(resolve, reject) {
> try {
> console.time("connecting");
> dbcp.connect()
> .then(runSelect)
> .then(returnResults)
> .then(resolve)
> .catch(reject);
> } catch (err) {
> reject(err);
> }
> }
Instead of using such methods write this.
console.time("connecting");
return dbcp.connect()
.then(runSelect)
.then(returnResults);
Every time, you run new dbHelper, you have a synchronized calls on the
require method. It could be possible that there is your bottle neck. All
things, that you require, you should require on the top of your module,
not in functions, methods.
I hope it will help a little bit.
Thomas
Am 10.04.2017 um 16:14 schrieb Victor Espina:
> Hi. I am new to node.js I am trying to create a REST service (using
> Express) that access data from a SQL Server. I am using mssql module
> with Tedious drivers. I created this module:
>
> /*
> dbhelper.js
> Helper para acceso a base de datos
>
> Victor Espina S
> NOI Quality Software, Chile
> */
>
> function dbhelper(params) {
>
> // Properties
> this.dbcp = params.dbcp; // DB ConnectionsPool object (created in app.js)
> this.config = require("../config");
>
> // Methods
> this.runQuery = runQuery;
> this.runSP = runSP;
> this.getRow = getRow;
> this.getScalar = getScalar;
>
> }
>
>
>
> // runQuery
> // Ejecuta una consulta y devuelve el resultado
> //
> function runQuery(query) {
> var sql = require('mssql');
> var dbcp = this.dbcp;
>
> var runSelect = function(pool) {
> console.timeEnd("connecting");
> return new Promise(function(resolve, reject) {
> console.time("request");
> var request = new sql.Request(pool);
> console.timeEnd("request");
> console.time("querying");
> request.query(query)
> .then(resolve)
> .catch(reject);
> });
> }
>
> var returnResults = function(result) {
> console.timeEnd("querying");
> return new Promise(function(resolve, reject) {
> console.time("closing");
> dbcp.close();
> console.timeEnd("closing");
> resolve(result);
> });
> }
>
> var resolver = function(resolve, reject) {
> try {
> console.time("connecting");
> dbcp.connect()
> .then(runSelect)
> .then(returnResults)
> .then(resolve)
> .catch(reject);
> } catch (err) {
> reject(err);
> }
> }
>
> return new Promise(resolver);
> }
>
> module.exports = dbhelper;
>
>
>
> and this is how I am using it:
>
> function dbTest(req, res, next) {
> var dbhelper = require("../modules/dbhelper");
> var db = new dbhelper({ dbcp: res.app.locals.dbcp });
> db.runQuery("select clave,texto from registro order by clave")
> .then(function(result) {
> res.send(result);
> });
> }
>
>
> Everything works great, but the response times are completely
> unaceptable: 10s for a 10 rows query!!! Check this image from the node
> noconsole after two consecutives requests to the server:
>
> <https://lh3.googleusercontent.com/-oL3nl7XVGJg/WOuTKkNhzHI/AAAAAAAAA20/JkO_M8BxS20fQbuG-DvjmJqm70tYzCfEgCLcB/s1600/Screen%2BShot%2B2017-04-10%2Bat%2B10.56.29%2BAM.png>
>
>
>
>
>
> Any ideas about what may be going on ? I tried this same query from a
> client app and it takes less than 1s. I am running node.js under OSX
> and the SQL Server (2016) is running under a virtualized Windows Server
> 2016, running in the same osx machine.
>
>
> Victor
>
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