The Layer On Top Of Google Search Web Rendering Service

There is an interesting tidbit you can learn about Google’s web rendering service (WRS) in the latest JavaScript SEO hangout with Martin Splitt of Google where Martin said he is “spilling the beans a little bit” by sharing that there is a layer on top of WRS that handles “prioritization, error retry, quality of service guarantees, caching
and it also interacts with a crawling subsystem to actually fetch things.”