Remove initial time.Sleep statement on SlidingWindow

[johnjones4]

Motivation

• When using SlidingWindow, the processing callback function does not begin receiving events until one full window duration has passed
• If the incoming channel closes before the time.Sleep has completed, the system will hang and not properly close its outgoing channel which can prevent graceful shutdown.
• Additionally, this is cumbersome for long duration windows whereas removing the time.Sleep statement allows the system to begin processing almost immediately

Modifications

• Removed time.Sleep
• An alternative implementation is use something like time.After to implement the full window delay so that the main loop can start immediately and properly handle the closed channel without hanging.

Verify change

• Make sure the change passes the CI checks.

[reugn]

Hi @johnjones4, thanks for raising this issue. At the moment, the flow blocks until the first window is elapsed even if the upstream has closed. The standard behavior for the sliding window operator is to wait for the first full window period before emitting elements downstream. #165 introduces a configuration option for partial results, which might be helpful if you're dealing with larger window sizes. Would that solve the problem you're encountering?

[johnjones4]

Yes love the configuration option approach. That would fit my needs. Thank you!