[RayService][Hotfix] Hotfix for Flaky Zero Downtime Rollout Test #1837
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Why are these changes needed?
The Zero Downtime Rollout Test is flaky for the following reason:
The current logic for the Zero Downtime Rollout operates as follows:
However, a critical issue is that the 'running' status merely indicates the readiness of the new RayCluster to serve traffic; it does not confirm that the serve service has begun redirecting traffic to the new RayCluster. As a result, requests sent after the status change to 'running' might still be responded to by the old RayCluster.
This scenario may lead to high-probability assertion errors in RayService CI tests, as responses expected from the new RayCluster may still coming from the old RayCluster. Some examples can be found here:
To mitigate this, and before refactoring the Rollout logic and redefine the of status, this PR adds delay to ensure the serve service is ready to redirect traffic to the new RayCluster.
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