Node.js => Leistungsherausforderungen

Verarbeiten von lange laufenden Abfragen mit Node

Da es sich bei Node um einen Singlethread handelt, ist eine Problemumgehung erforderlich, wenn es zu langwierigen Berechnungen kommt.

Hinweis: Dies ist ein Beispiel für die Ausführung. Vergessen Sie nicht, jQuery zu installieren und die erforderlichen Module zu installieren.

Hauptlogik dieses Beispiels:

Client sendet Anforderung an den Server.
Der Server startet die Routine in einer separaten Knoteninstanz und sendet eine sofortige Antwort mit der zugehörigen Task-ID zurück.
Der Client sendet ständig Überprüfungen an den Server, um Statusaktualisierungen der angegebenen Task-ID zu überprüfen.

Projektstruktur:

    project
    │   package.json
    │   index.html    
    │
    ├───js
    │      main.js
    │      jquery-1.12.0.min.js
    │   
    └───srv
        │    app.js
        ├─── models
        │      task.js
        └─── tasks
               data-processor.js

app.js:

var express     = require('express');
var app         = express();
var http        = require('http').Server(app);
var mongoose    = require('mongoose');
var bodyParser  = require('body-parser');

var childProcess= require('child_process');

var Task        = require('./models/task');

app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());

app.use(express.static(__dirname + '/../'));

app.get('/', function(request, response){
    response.render('index.html');
});

//route for the request itself
app.post('/long-running-request', function(request, response){
    //create new task item for status tracking
    var t = new Task({ status: 'Starting ...' });
    
    t.save(function(err, task){
        //create new instance of node for running separate task in another thread
        taskProcessor = childProcess.fork('./srv/tasks/data-processor.js');

        //process the messages comming from the task processor
        taskProcessor.on('message', function(msg){
            task.status = msg.status;
            task.save();
        }.bind(this));

        //remove previously openned node instance when we finished
        taskProcessor.on('close', function(msg){
            this.kill();
        });

        //send some params to our separate task
        var params = {
            message: 'Hello from main thread'
        };

        taskProcessor.send(params);
        response.status(200).json(task);
    });
});

//route to check is the request is finished the calculations
app.post('/is-ready', function(request, response){
    Task
        .findById(request.body.id)
        .exec(function(err, task){
            response.status(200).json(task);
        });
});

mongoose.connect('mongodb://localhost/test');
http.listen('1234');

task.js:

var mongoose    = require('mongoose');

var taskSchema = mongoose.Schema({
    status: {
        type: String
    }
});

mongoose.model('Task', taskSchema);

module.exports  = mongoose.model('Task');

Datenprozessor.js:

process.on('message', function(msg){
    init = function(){
        processData(msg.message);
    }.bind(this)();
    
    function processData(message){
        //send status update to the main app
        process.send({ status: 'We have started processing your data.' });

        //long calculations ..
        setTimeout(function(){
            process.send({ status: 'Done!' });
            
            //notify node, that we are done with this task
            process.disconnect();
        }, 5000);
    }
});

process.on('uncaughtException',function(err){
    console.log("Error happened: " + err.message + "\n" + err.stack + ".\n");
    console.log("Gracefully finish the routine.");
});

index.html:

<!DOCTYPE html>
<html>
    <head>
        <script src="./js/jquery-1.12.0.min.js"></script>
        <script src="./js/main.js"></script>
    </head>
    <body>
        <p>Example of processing long-running node requests.</p>
        <button id="go" type="button">Run</button>
        
        <br />
        
        <p>Log:</p>
        <textarea id="log" rows="20" cols="50"></textarea>    
    </body>
</html>

main.js:

$(document).on('ready', function(){
    
    $('#go').on('click', function(e){
        //clear log
        $("#log").val('');
        
        $.post("/long-running-request", {some_params: 'params' })
            .done(function(task){
                $("#log").val( $("#log").val() + '\n' + task.status);
                
                //function for tracking the status of the task
                function updateStatus(){
                    $.post("/is-ready", {id: task._id })
                        .done(function(response){
                            $("#log").val( $("#log").val() + '\n' + response.status);
                            
                            if(response.status != 'Done!'){
                                checkTaskTimeout = setTimeout(updateStatus, 500);
                            }
                        });
                }
                
                //start checking the task
                var checkTaskTimeout = setTimeout(updateStatus, 100);
            });
    });
});

package.json:

{
  "name": "nodeProcessor",
  "dependencies": {
    "body-parser": "^1.15.2",
    "express": "^4.14.0",
    "html": "0.0.10",
    "mongoose": "^4.5.5"
  }
}

Haftungsausschluss: Dieses Beispiel soll Ihnen eine grundlegende Idee geben. Um es in der Produktionsumgebung einsetzen zu können, sind Verbesserungen erforderlich.

Modified text is an extract of the original Stack Overflow Documentation

Lizenziert unter CC BY-SA 3.0

Nicht angeschlossen an Stack Overflow

Node.js
Leistungsherausforderungen

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Verarbeiten von lange laufenden Abfragen mit Node