use spawn_blocking for parsing

[Geal]

This leverages the work that @xuorig started in #5235 with a number of necessary follow-up fixes to get it into the shape we'll need to land it.

I have checked manually that the span duplication in the snapshot has no impact on traces reported to aggregators, it's more of an artifact of our way to gather spans in the test.

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Checklist

Complete the checklist (and note appropriate exceptions) before the PR is marked ready-for-review.

• Changes are compatible¹
• Documentation² completed
• Performance impact assessed and acceptable
• Tests added and passing³
  • Unit Tests
  • Integration Tests
  • Manual Tests

Exceptions

Note any exceptions here

Notes

Footnotes

1. It may be appropriate to bring upcoming changes to the attention of other (impacted) groups. Please endeavour to do this before seeking PR approval. The mechanism for doing this will vary considerably, so use your judgement as to how and when to do this. ↩

2. Configuration is an important part of many changes. Where applicable please try to document configuration examples. ↩

3. Tick whichever testing boxes are applicable. If you are adding Manual Tests, please document the manual testing (extensively) in the Exceptions. ↩

[router-perf]

CI performance tests

• const - Basic stress test that runs with a constant number of users
• demand-control-instrumented - A copy of the step test, but with demand control monitoring and metrics enabled
• demand-control-uninstrumented - A copy of the step test, but with demand control monitoring enabled
• enhanced-signature - Enhanced signature enabled
• events - Stress test for events with a lot of users and deduplication ENABLED
• events_big_cap_high_rate - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity
• events_big_cap_high_rate_callback - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity using callback mode
• events_callback - Stress test for events with a lot of users and deduplication ENABLED in callback mode
• events_without_dedup - Stress test for events with a lot of users and deduplication DISABLED
• events_without_dedup_callback - Stress test for events with a lot of users and deduplication DISABLED using callback mode
• extended-reference-mode - Extended reference mode enabled
• large-request - Stress test with a 1 MB request payload
• no-tracing - Basic stress test, no tracing
• reload - Reload test over a long period of time at a constant rate of users
• step-jemalloc-tuning - Clone of the basic stress test for jemalloc tuning
• step-local-metrics - Field stats that are generated from the router rather than FTV1
• step-with-prometheus - A copy of the step test with the Prometheus metrics exporter enabled
• step - Basic stress test that steps up the number of users over time
• xlarge-request - Stress test with 10 MB request payload
• xxlarge-request - Stress test with 100 MB request payload

[Geal]

it looks like there's some flakiness in the tests with the snapshots https://app.circleci.com/pipelines/github/apollographql/router/23631/workflows/0230bc91-f65c-47a1-ae33-6128fae26325/jobs/165914?invite=true#step-117-361965_43
@garypen if I cannot fix that tomorrow, can you take over that PR?

[abernix]

There is indeed an on-going something or another in the tests. @BrynCooke did try to look at this today, but will not be around for the next couple weeks, and I'm not sure will get back to it.

I will highlight that there is still conversation that wasn't answered from the original PR that might be worth discussing:

@xuorig wrote:

Few other questions:

• Is specific back pressure for the spawn blocking needed at this level? I'm thinking this is fine for now, back pressure can happen as a concurrency limiter / rate limiter at ingress.
• Would a wait map similar to planning make sense eventually here?

[Geal]

Thanks @garypen for finishing that one

[abernix]

This PR is causing some tests to flake at a somewhat pronounced rate. We believe it's just actually the tests, or the way we tested, but we'll revert this for now.