djones6
commented
5 years ago Looks like URLSession.shared.finishTasksAndInvalidate() is having an effect on Linux (contrary to the documentation).
This is probably because in Foundation, finishTasksAndInvalidate was implemented first (https://github.com/apple/swift-corelibs-foundation/pull/640) and shared was more recent (https://github.com/apple/swift-corelibs-foundation/pull/1365), and I guess this subtlety may have been missed.
In the meantime we should be able to keep track of whether we're using the shared session or not, and just avoid calling the function if so.
ianpartridge
Andrew-Lees11
This pull request fixes the memory leak caused by creating multiple URLSessions when making requests. There are three cases where URLSession holds on to memory:
When creating a URLSession, Every session will create an SSL cache associated to your app, which takes 10 minutes to clear, regardless of it you clear the session. For this reason you are not intended to create a new session for each request. For requests without a delegate, I have fixed this by using URLSession.shared. This uses a shared singleton session for all the requests.
When creating a URLSession with a delegate: "The session object keeps a strong reference to the delegate until your app exits or explicitly invalidates the session. If you do not invalidate the session by calling the invalidateAndCancel() or finishTasksAndInvalidate() method, your app leaks memory until it exits." To solve this I have added a call to the session finishTasksAndInvalidate() to the RestRequest deinitialiser. (For URLSession.shared, this call doesn't do anything)
When using Circuit Breaker, The rest request is never deallocated . As raises in issue #59, When you use a CircuitBreaker in the RestRequest references circuit breaker that references handleInvocation that references the request meaning it isn't deallocated. This Leak will be address in a future PR.