Why am I seeing "waiting on server" on query traces?

When viewing a query trace in Apollo Studio, you might see "waiting on server" as part of the timeline.

This indicates that the gateway is waiting for a blocking process on a subgraph server to complete before it can begin fulfilling the query.

In these scenarios, we recommend referring to the best practices for increasing the performance of your server's specific language or framework.

For example, Apollo Server runs on Node.js, a single-threaded system. If a blocking middleware slows things down _before_ a server starts handling a GraphQL request, that will affect the wait time in the trace.

Regardless of your framework, we recommend limiting your server's required pre-processing before handling a GraphQL request.