socketTimeout trigger on empty lines

[ronag]

const { Client } = require('./')
const stream = require('stream')

// CouchDB server
const client = new Client('http://localhost:5984', {
  socketTimeout: 15e3,
  headersTimeout: 15e3
})

client.stream({
  method: 'GET',
  path: '/nxt/_changes?feed=continuous&heartbeat=5000'
}, () => new stream.Writable({
  write (chunk, encoding, callback) {
    console.error(String(chunk))
    callback()
  }
}))

let x = 0
setInterval(() => {
  console.error("# ", x++)
}, 1e3)

Also logging inside kOnBody and kOnExecute in Parser will give the following output:

kOnExecute
#  0
#  1
#  2
#  3
#  4
kOnBody


kOnExecute
#  5
#  6
#  7
#  8
#  9
kOnBody


kOnExecute
#  10
#  11
#  12
#  13
#  14
kOnBody


#  15
#  16
#  17
#  18
#  19
kOnBody


#  20
#  21
#  22
#  23
#  24
kOnBody

Notice how kOnExecute does not seem to be invoked on empty lines?

[ronag]

So the response from the server looks something like this:

HTTP/1.1 200 OK\r\n
Transfer-Encoding: chunked\r\n
Server: CouchDB/1.6.1 (Erlang OTP/17)\r\n
Date: Wed, 29 Jul 2020 10:06:14 GMT\r\n
Content-Type: text/plain; charset=utf-8\r\n
Cache-Control: must-revalidate\r\n
\r\n
1\r\n
\n\r\n
1\r\n
\n\r\n
1\r\n
\n\r\n
1\r\n
\n\r\n

Basically it's long polling chunked response which sends \n as a heartbeat. It seems to me that for some reason a line of \n in some combination doesn't invoke kOnExecute but does invoke kOnBody.

Maybe related https://github.com/nodejs/node/blob/master/src/node_http_parser.cc#L665?

Might also explain #268

@indutny @addaleax Do you have any ideas?

I don't think we currently encounter this in node core since the node http client doesn't use the consume API.

[ronag]

Added a workaround. Would be interesting to fix "properly".

[ronag]

Node bug nodejs/node#34578