Socket hang up error

[amishas157]

I am using vt2geojson for requesting vector tiles geojson in osm-compare, to get a set of features but getting following issue in few requests.
Traceback:

/app/node_modules/@mapbox/vt2geojson/index.js:34
            if (err) throw err;
                     ^
Error: socket hang up
    at createHangUpError (_http_client.js:250:15)
    at Socket.socketOnEnd (_http_client.js:342:23)
    at emitNone (events.js:91:20)
    at Socket.emit (events.js:185:7)
    at endReadableNT (_stream_readable.js:926:12)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)
    at process._tickDomainCallback (internal/process/next_tick.js:122:9)

The code is here, where I am making the query.

Not sure what this means and what's causing this issue. Would be great to get some help debugging it.

cc @mapsam

[amishas157]

Per voice w/ @lukasmartinelli , seems like error coming due to request getting timeout. To resolve we can try few things:

• returning the callback with error, from vt2geojson instead of throwing it.
• If request fails, retry it using node-retry.

Challenges: Hard to reproduce the issue locally :(

cc @batpad

[geohacker]

What if we write a script to run vt2geojson fast, to see if that can reproduce the issue? But all of the above sounds good to me.

[amishas157]

@geohacker
This is a small script which I used to test it locally https://jsfiddle.net/c6ej7ekc/
And on running it , got the following error:

/Users/AmishaSingla/Documents/osm-compare/node_modules/@mapbox/vt2geojson/index.js:36
                throw err;
                ^

Error: getaddrinfo ENOTFOUND a.tiles.mapbox.com a.tiles.mapbox.com:80
    at errnoException (dns.js:27:10)
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:78:26)

And from this module, seems like this error also belongs to the same family.

When the connection fails with one of ECONNRESET, ENOTFOUND, ESOCKETTIMEDOUT, ETIMEDOUT, ECONNREFUSED, EHOSTUNREACH, EPIPE, EAI_AGAIN or when an HTTP 5xx error occurrs, the request will automatically be re-attempted as these are often recoverable errors and will go away on retry

[amishas157]

Retrying the request for 5 times if the first request fails.
Here is the patch: https://github.com/mapbox/osm-compare/blob/feature-overlaps/lib/get_vector_tile_features.js#L27-#L39

[amishas157]

Seems like we are not getting error anymore, as whenever request fails #1 log shows that the number of retry attempts done to fetch tiles.

Next action

• Check if we can merge this PR: Return error #14

[amishas157]

Check if we can merge this PR: #14

The PR is merged . Issue good to close now.