AWS launched [Lambda Managed
Instances](https://docs.aws.amazon.com/lambda/latest/dg/lambda-managed-instances.html),
i.e Lambda functions running on EC2 instances.
This comes with [a major change in the programming
model](https://docs.aws.amazon.com/lambda/latest/dg/lambda-managed-instances.html#lambda-managed-instances-concurrency-model)
as function handlers are now allowed to run concurrently on the same
machine (multiple in flight events being processed in parallel in the
same execution environment). The maximum concurrency per runtime
environment is controlled by the user.
This PR adds support for running multiple Runtime Interface Clients
(RICs) concurrently when deployed on Lambda Managed Instances, enabling
the runtime to handle multiple invocations simultaneously within a
single execution environment.
This PR is a followup to
https://github.com/awslabs/swift-aws-lambda-runtime/pull/617 which used
another approach to support Lambda Managed Instances by changing the
public API and requiring that all handlers must conform to `Sendable`.
The original PR was closed as we agreed that only a fraction of the
Lambda functions will be deployed on EC2 and it was not worth adding a
`Sendable` requirement for all.
**Changes**
- **Introduced thread-safe LambdaManagedRuntime**: Created new
Sendable-conforming runtime class that supports concurrent handler
execution with atomic guards to prevent multiple runtime instances and
thread-safe handler requirements (`Handler: StreamingLambdaHandler &
Sendable`)
- **Implemented ServiceLifecycle integration**: Added managed runtime
support for structured concurrency lifecycle management, allowing proper
startup/shutdown coordination in multi-concurrent environments
This PR contains only changes to the core runtime, convenience
functions, handlers, adapters, and a comprehensive example will be added
in a follow up PR.
**Context**
Lambda Managed Instances support multi-concurrent invocations where
multiple invocations execute simultaneously within the same execution
environment. The runtime now detects the configured concurrency level
and launches the appropriate number of RICs to handle concurrent
requests efficiently.
When `AWS_LAMBDA_MAX_CONCURRENCY` is 1 or unset, the runtime maintains
the existing single-threaded behaviour for optimal performance on
traditional Lambda deployments.
---------
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Sebastien Stormacq <stormacq@amazon.lu>
- Use the new Swift 6 `@available` macro to remove requirement on
`.platform` in Package.swift.
- DRY: define the swift settings once for all in `Package.swift`
### Motivation:
- Remove the requirement to build on macOS 15 in `Package.swift`. This
allows library builders and end users to be more flexible on their
dependency requirements.
- The code is optionally compiled on macOS 15 and Linux, but SPM don't
enforce it anymore.
- Avoid repeating ourself. Be sure the same settings are applied on all
targets.
### Modifications:
- Create a `var swiftSetting: [SwiftSettings]` and reuse it for all
targets.
- Use `AvailabilityMacro=LambdaSwift 2.0:macOS 15.0`
- Add this on top of the majority struct / classes
```swift
#if swift(>=6.1)
@available(LambdaSwift 2.0, *)
#endif
```
### Result:
When using Swift 6.1, there is no more SPM dependency on macOS 15
Fabian Fett