Tracer implementing Closable

[carlosalberto]

In OT, Tracer implements Closable, which lets users flush pending Spans and dispose related resources.

Is there any point against this for the new API? I don't see any, but let me know ;)

[tedsuo]

In OT, It was helpful to close the tracer without knowing the underlying implementation.

@bogdandrutu please add Closable unless you object.

[bogdandrutu]

I think close is not good because the Tracer is shared between multiple threads and race conditions can happen (users need to synchronize the close call, or make sure they close after all the usages of the Tracer). I probably suggest having a "Flush" method if that is needed for tests or for the shutdown hook. Also a good question is if the Flush should be a method on the Tracer implementation or on the main Tracer interface.

[carlosalberto]

A flush method is ok - essentially we need a way to let remaining Span instances be sent in case the service is about to shutdown.

[tedsuo]

We need to gather use cases to better understand if Close and/or Flush should be on the Tracer interface.

Main use case:

• Shutdown code

[bogdandrutu]

We do have a shutdown method on the SDK. I think the shutdown belongs to the implementation that is used.