Async routes that have a body always exhibit thread-unsafety

[weissi]

Vapor's Request is not thread safe which means that nothing must call request.<anything> unless you're guaranteed to be on request.eventLoop already (until #2951 is fixed).

But Vapor's own async code doesn't respect that rule.

For example this code here

vapor/Sources/Vapor/Concurrency/RoutesBuilder+Concurrency.swift

Line 133 in 4709b92

_ = try await request.body.collect(max: max?.value ?? request.application.routes.defaultMaxBodySize.value).get()

needs to be

            if case .collect(let max) = body, request.body.data == nil {
                try await request.eventLoop.flatSubmit {
                    request.body.collect(max: max?.value ?? request.application.routes.defaultMaxBodySize.value)
                }.get()
            }

Obviously the above suggestion is just bandaid, Request has to become thread safe for it to be viable to use the async support.