Cancel resolver tasks if execution of an operation is terminated

首先跟踪异步 GraphQL 操作的执行，以及当不可为空的 resolver 失败时 resolver 任务是如何被调度的。复现 issue #3414 中描述的 Strawberry 场景；完成的标准是：不再需要的 resolver 任务会在执行终止前被取消，并且不会在响应返回或生命周期清理后继续运行。

TL;DR

Would it be possible to cancel outstanding resolver tasks as soon as before execution of a GraphQL operation is terminated? Outstanding / unused tasks can happen as a result of an incoercible field resolver error.

These outstanding tasks can run well after lifecycle hooks responsible for cleaning up their context have completed. As a result, they often fail and cause a lot of noisy errors for us.

More details

Hello!

I'm coming from the strawberry-graphql project. We're running into a problem with abandoned resolver tasks not being cancelled, and thus failing in unpredictable ways.

Strawberry has an extensions framework which allows you to wrap the execution phase of your operation processing in hooks – running code before and after execution of resolvers. We use these hooks to manage (set up and tear down) some state needed by the resolvers.

However, when a resolver of a non-nullable field fails, it may lead to the results of some other resolvers being no longer necessary. It appears that graphql-core will then short-circuit returning a result, while the no-longer-necessary resolvers are still running. We see that they can continue running well after the HTTP response was returned.

The problem is that Strawberry's lifecycle hooks (and I also imagine - the webserver's) would have completed by that time. As a result, we do things like terminate the DB session – making it very likely that these outstanding tasks will fail with various esoteric errors. This causes a lot of noise in our observability suite – which we'd love to avoid.

See https://github.com/strawberry-graphql/strawberry/issues/3414 for more details, and https://github.com/strawberry-graphql/strawberry/issues/3414#issuecomment-2012060461 for the comment which recommends I report the issue here.