Collector Run should exit quickly if shutdown was called prior

[cpheps]

Describe the bug
Currently if Shutdown is called before Run all this startup code runs before runAndWaitForShutdownEvent which will then process the shutdown.

Steps to reproduce

1. Created collector
2. Call Shutdown
3. Call Run

What did you expect to see?
Collector not attempt to run startup/configure code and exit early.

What did you see instead?
Startup code was run then exited.

What version did you use?
Version: v0.45.0

What config did you use?
Config: any valid config

Environment
OS: MacOS 12.2
Compiler(if manually compiled): go 1.17.6

Additional context
Action item from #4878

[dmitryax]

cc @djaglowski

[Chinwendu20]

Could you please assign this to me?

[Chinwendu20]

According to the code comments, run should not be called after shutdown

[cpheps]

@Chinwendu20 This ticket is to basically make a short circuit path in Run where if a given instance of a Collector is Shutdown then subsequent calls to run should detect this and exit quickly. There's a lot of logic that happens in Run before it would detect that it was already shut down.

I think there's a valid question on if Run should return and error if it's used after Shutdown is called. I believe it should as it would provide helpful context for the caller as to why didn't execute properly.

[cpheps]

@dmitryax Can you assign @Chinwendu20 to this issue please?

[jpkrohling]

Collector not attempt to run startup/configure code and exit early.

Is this even what we want? I was under the impression that we should be able to stop/start the collector whenever we wanted.

@tigrannajaryan, I'm pretty sure I got this from you a few years ago :-) Do you think that's still valid to this day?

[cpheps]

@jpkrohling I was under the impression you could start multiple instance of the collector per process but not a single instance over and over. This would make sure a single instance exits early rather than doing a full startup before closing.

[atoulme]

The comment on Run now says:

// Consecutive calls to Run are not allowed, Run shouldn't be called once a collector is shut down.

See

opentelemetry-collector/otelcol/collector.go

Line 227 in ecd837e

// Consecutive calls to Run are not allowed, Run shouldn't be called once a collector is shut down.

I believe this means the use case you describe is not supported. I propose to close this issue as not planned, please comment or reopen the issue if you disagree.