scheduler: perform feasibility checks for system canaries before computing placements #26953
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tgross
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Two groups on the same job cannot both have a static port assignment, but this ends up getting configured in the update block test for system deployments. This test setup bug has complicated landing the fix in #26953.
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Two groups on the same job cannot both have a static port assignment, but this ends up getting configured in the update block test for system deployments. This test setup bug has complicated landing the fix in #26953.
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… state Previously we copied the behavior found in the generic scheduler, where we rely on reconciler results to decide if there's enough placements made. In the system scheduler we always know exactly how many placements there should be based on the DesiredTotal field of the deployment state, so a better way to check completeness of the deployment is to simplify it and base on dstate alone.
…iler In contrast to the cluster reconciler, in the node reconciler we go node-by-node as opposed to alloc-by-alloc, and thus the state of the reconciler has to be managed differently. If we override old deployments on every run of `cancelUnneededDeployments`, we end up with unnecessarily created deployments for job version that already had them.
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Canaries for system jobs are placed on a
tg.update.canarypercent of eligible nodes. Some of these nodes may not be feasible, and until now we removed infeasible nodes during placement computation. However, if it happens to be that the first eligible node we picked to place a canary on is infeasible, this will lead to the scheduler halting deployment.The solution presented here simplifies canary deployments: initially, system jobs that use canary updates get allocations placed on all eligible nodes, but before we start computing actual placements, a method called
evictUnneededCanariesis called (much likeevictAndPlaceis for honoring MaxParallel) which removes those canary placements that are not needed. We also change the behavior ofcomputePlacementswhich no longer performs node feasibility checks, as these are performed earlier for every allocation and node. This way we get accurate counts of all feasible nodes that let us correctly set deployment state fields.Fixes: #26885
Fixes: #26886