Express.js Response Timeout

78
votes

PROBLEM

I've been looking for request/response timeouts for Express.js but everything seems to be related to the connection rather than the request/response itself.

If a request is taking a long time, it should be timed out. Obviously this shouldn't happen but even a simple mistake as having a route handler without a call to the callback or without res.send(), the browser will keep waiting for a reply forever.

An empty route handler is a perfect example of this.

app.get('/sessions/', function(req, res, callback){});

FIX

I added the following before app.use(app,router); and it seemed to add the timeout functionality. Does anyone have any experience/opinion on this?

app.use(function(req, res, next){
    res.setTimeout(120000, function(){
        console.log('Request has timed out.');
            res.send(408);
        });

    next();
});

Note that I've set the timeout to 2 minutes.

7
node.jsexpresstimeoutresponsesettimeout
I would use this for development purposes only – I can't think of a single use case where you would want to ship production code with empty routes. – srquinn
If course, my point with that is that its possible to have an issue where the request would just keep waiting. Bugs happen. I'm just trying to set a response timeout just in case. – Xerri
Gotcha – see answer below – srquinn
empty routes as a trap for web spiders? – prototype
This 'feature' actually came quite useful when I was trying to use Express.js (well, actually json-server) to build a test service with the purpose of simulating / inducing all manners of error conditions on the server side. Most such errors corresponded to HTTP status codes (e.g. Bad Request), yes, but I also wanted to cause a SocketTimeoutException on the caller end. – Ferenc Dósa-Rácz

7 Answers

80
votes

There is already a Connect Middleware for Timeout support:

var timeout = express.timeout // express v3 and below
var timeout = require('connect-timeout'); //express v4

app.use(timeout(120000));
app.use(haltOnTimedout);

function haltOnTimedout(req, res, next){
  if (!req.timedout) next();
}

If you plan on using the Timeout middleware as a top-level middleware like above, the haltOnTimedOut middleware needs to be the last middleware defined in the stack and is used for catching the timeout event. Thanks @Aichholzer for the update.

Side Note:

Keep in mind that if you roll your own timeout middleware, 4xx status codes are for client errors and 5xx are for server errors. 408s are reserved for when:

The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time.

50
votes

You don't need other npm modules to do this

var server = app.listen();
server.setTimeout(500000);

inspired by https://github.com/expressjs/express/issues/3330

or

app.use(function(req, res, next){
    req.setTimeout(500000, function(){
        // call back function is called when request timed out.
    });
    next();
});
33
votes

An update if one is using Express 4.2 then the timeout middleware has been removed so need to manually add it with

npm install connect-timeout

and in the code it has to be (Edited as per comment, how to include it in the code)

 var timeout = require('connect-timeout');
 app.use(timeout('100s'));
4
votes

In case you would like to use timeout middleware and exclude a specific route:

var timeout = require('connect-timeout');
app.use(timeout('5s')); //set 5s timeout for all requests

app.use('/my_route', function(req, res, next) {
    req.clearTimeout(); // clear request timeout
    req.setTimeout(20000); //set a 20s timeout for this request
    next();
}).get('/my_route', function(req, res) {
    //do something that takes a long time
});
-1
votes

You can try:

return await new Promise((resolve) =>
  setTimeout(() => {
    resolve(resp);
  }, 3000),
);

In above code, 3000 = 3 sec. Change it according to your requirement.

I have not tried for very long scenarios though. Let me know the results in comments.

-23
votes

Before you set your routes, add the code:

app.all('*', function(req, res, next) {
    setTimeout(function() {
        next();
    }, 120000); // 120 seconds
});