wp_cron with nginx (499 error)

I am running wordpress on nginx, and found I had a lot of 499 errors in the error logs for requests to wp_cron.php. Looking into this, I found some advice that suggested increasing the cron timeout from 0.001s and also making PHP sleep for a short time.

I increased the cron timeout to 0.1s and added a usleep for the same amount of time. Now the majority of requests to wp_cron.php are recording 200 okay and not 499.

But, I was wondering if the 499 error means that the cron wasn’t working? If the client terminates the connection before the server could finish responding, does the process handling the cron get terminated before it can complete? Or does the process carry on even after the client has closed the connection?

P.S. I am not running any caching on the nginx side.