sendFile "Error: read ECONNRESET", express >= 4.9

[hex7c0]

Hi guys,
I have an issue (no crash) similar to #2433 , but with different output
when I send a "big" file ~12.6 MB with sendFile
and browser splits the request in 3 chunks (1 HTTP code 200 + 2 HTTP code 206)

tested with:

• express ~4.9, ~4.10, ~4.11, ~4.12,
• node ~0.12, iojs ~1.1
• chrome 41.0
• with express ~4.8, I haven't this error

error:

Error: read ECONNRESET
    at exports._errnoException (util.js:734:11)
    at TCP.onread (net.js:538:26)

[hex7c0]

here output with debug flag
express ~4.12, iojs ~1.1

thanks

[dougwilson]

There is no issue here; only in the version you don't get this error is because we never used to expose that error before.

You are seeing normal behavior, especially for PDF readers: they first make a non-ranged request, read the top of the file and cancel the request (causing node.js to emit that error). They then make multiple ranged requests based on binary data at the top of the PDF they saw before aborting the first request.

[dougwilson]

Also, you should not see this error if you call res.sendFile with no callback. If you see this error printed and you are not the one printing it, then it is a bug (and please paste the code you have).

[dougwilson]

The following is from the 4.9.0 change log:

Invoke callback for sendfile when client aborts
Applies to res.sendFile , res.sendfile , and res.download
err will be populated with request aborted error

[hex7c0]

thanks for the reply
yes, I know the flow for PDF readers

but I don't print this error (and this is the reason for the issue)
the code is equal to previous issue

var app = require('express')();
app.get('/', function(req, res) {

  res.sendFile(__dirname + '/a.pdf');
});
app.listen(3000);

[dougwilson]

Ok, so after reviewing the log you posted (thank you!) I have a few questions:

1. Can you run the same thing against Node.js rather than io.js, just so I can see the same stacks I can see (I cannot run io.js myself to try and reproduce).
2. Can you, at the top of your app, add this: (function(p){var d=p.destroy;p.destroy=function(){console.trace('NET destroy');return d.apply(this,arguments)}})(require('net').Socket.prototype);
3. Are you calling server.close() anywhere in your code?

[dougwilson]

I was able to reproduce! :) So I don't think I need you to do any information gathering.