Karma 0.13.19 taking long time to complete when run via gulp

I am opening a new ticket as this seems to be fallout from #1782 and the socket.io upgrade to 1.4.0.

I’ve just noticed a side effect from upgrading to 0.13.19; gulp karma test tasks take much longer to exit after the test run.

gulp.task('test:ng', function(done) {
  new Server({
    configFile: __dirname + '/karma.conf.js',
    singleRun: true
  }, done).start();
});

Previously the above task used to complete immediately after tests have completed. on 0.13.9, there is a pause of ~30 seconds after the karma runner completes the tests and the task exits.

gulp.task('test:ng', function(done) {
  new Server({
    configFile: __dirname + '/karma.conf.js',
    singleRun: true
  }, function() {
    console.log('done');
    done();
  }).start();
});

The above outputs done to the console but the gulp task still doesn’t complete until after ~30 seconds.

cc @nazar

[fegemo]

I am also seeing this on version 1.1.1.

[henryptung]

@nazar Seeing the same thing here.

After doing some digging:

The 30 second timeout is from https://github.com/websockets/ws/blob/master/lib/WebSocket.js#L129, where if the WebSocket is closed uncleanly (without close acknowledgement from the client), the socket goes into limbo mode, waiting to receive this ack before fully closing out.

It seems like Karma, in singleRun mode, will try to kill the browser immediately upon browser_complete, rather than first closing the socket and waiting for completion of socket close. Ultimately, Karma will try to push some buffered information down the socket (trying to inform the browser of its own startup, actually), which hits EPIPE, and triggers this delayed close mode of the socket, keeping the Karma process alive an additional 30 seconds.

Regarding PhantomJS versions, I was able to reproduce this both with PhantomJS 2.x and with PhantomJS 1.9.8 + karma-phantomjs-launcher 0.2.3. Current workaround is to revert to karma 0.13.9, karma-phantomjs-launcher 0.2.1 which we were previously using.