Slow Yoga response time

[kefniark]

Description

Hello, there. Recently I noticed some weird response time on one of our service, which is using graphql-yoga (up-to-date):

node@18
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And the implementation is mostly based on https://the-guild.dev/graphql/yoga-server/docs/integrations/integration-with-fastify, nothing crazy.
Basically my problem is that the response time of the same query seem all over the place 50~150ms for consecutive calls.
Most are 50ms, but some queries are x2 or x3 slower for no apparent reason.

I suspected almost everything else related to networking (google cloud, fastify, prisma) first, but after putting few logs / tracing I realized, all this time seem to come from inside yoga:

const response = await yoga.handleNodeRequest(req, { req, reply })

Measure

So here is an example of this phenomenon, the same graphql query done twice in a row.
This endpoint simple return me data for a datatable (~20 rows and ~20kb raw response).

Query 1 (~59ms)

• before resolver ~7ms
• resolver ~4.8 ms
• after resolver ~47ms

Query 2 (~183ms)

• before resolver ~6ms
• resolver ~4ms
• after resolver ~173ms

We can see in my setup, the time spent in parsing, building context or resolver times are quite small, stable and consistent.
But the time spent between the resolver ended and the json result passed to fastify handler seem quite long, most of the time it represent the majority of the endpoint duration.

And if I continue to refresh the same query, I can see timing all over the place

57ms, 59ms, 111ms, 64ms, 75ms, 58ms, 136ms, 64ms, 56ms, 63ms, 57ms, 175ms, 63ms ...

Question

I already tried few things like disabling all dev options graphiql & co, disabling every plugin, disabling cache, ... but absolutely no effect.

• Does anyone know what's going on during yoga serialization, is it normal to be so time consuming (apparently longer than everything else in this query) and is there anything doable ?
• Is there more specific tracing or debug option to understand what's going on in yoga internal?

[kefniark]

Ok I found out where it comes from, a coworker added a field resolver which is using a 3rd party api.
This is slow and was not counted in resolver execution time.