concepts:
kubectl/dashboard/client.go/client.py, apiserver, kube controller manager, informer, reflector, work queue, resource, gabarge collector, graph builder, node
文字表达能力有限，更详细请看大纲图
可交互的大纲图链接如下
https://www.processon.com/out...
apiserver process flow:
pre:
GenericAPIServer.InstallAPIGroup
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APIGroupVersion.InstallREST
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APIInstaller.Install
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registerResourceHandlers
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actions = appendIf(actions, action{"DELETE", itemPath, nameParams, namer, false}, isGracefulDeleter)|
discovery.NewAPIVersionHandler.AddToWebService
main flow:
endpoints.installer.restfulDeleteResource
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handlers.DeleteResource
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GracefulDeleter.Delete
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generic.registry.store.Delete
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rest.delete.BeforeDelete
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objectMeta.SetDeletionTimestamp
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objectMeta.SetDeletionGracePeriodSeconds
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deletionFinalizersForGarbageCollection（add delete finalizers）
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updateForGracefulDeletionAndFinalizers
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store.Storage.GuaranteedUpdate(deletionTimestamp, finalizers)
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if deleteImmediately
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e.Storage.Delete delete from etcd
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finalizeDelete ran after delete hook
garbage collector process flow:
startGarbageCollectorController
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discoveryClient — NewMemCacheClient
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GetDeletableResources(APIResources that can delete watch list)
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NewGarbageCollector
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attemptToDelete(NewNamedRateLimitingQueue 单个条目 10 ms - 1000s 的指数增长个重试延迟，总队列 qps 10， 桶大小 100 的令牌桶限流)
attemptToOrphan(NewNamedRateLimitingQueue)
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absentOwnerCache(UID lru cache with max size 500, 1.16.18 后改为了 objectReference)
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gc(GarbageCollector)
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gb(GraphBuilder)
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graphChanges(NewNamedRateLimitingQueue)
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gb.syncMonitors(attempt to create a monitor for each resource, called when start or stop gb)
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go garbageCollector.Run
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stopCh(do goroutine exit and worker exit)
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go GraphBuilder.Run(stopCh)
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startMonitors (start inform)
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gb.sharedInformers.Start(gb.stopCh)
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go monitor.Run (start listAndWatch resource)
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gb.runProcessGraphChanges (a single thread worker)
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processGraphChanges. (PR return of this function is useless, doesn't exist in the graph Info should be warning)
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gb.graphChanges.Get()
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gb.uidToNode.Read (check if node exists)
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if found
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node.markObserved
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switch !found and (event == add or event == update):
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gb.insertNode(newNode)
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addDependentToOwners — reverse add dependent to owners based on current node’s ownerReferences
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if owner not exists
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attemptToDelete — verify if owner is a deleted node
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gb.processTransitions — verify if it is being delete because reflector may combine create delete event into one event(PR: maybe this event should not be combined)
switch found and (event == add or event == update):
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referencesDiffs — PR TODO: profile this function to see if a naive N^2 algorithm performs better when the number of references is small.
switch event == delete
\
removeNode
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uidToNode.Delete
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removeDependentFromOwners（from uidToNode）
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gb.attemptToDelete.Add(dependents — children)
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gb.attemptToDelete.Add(ownerNodes) — PR: check and update ownerNode dependents rather than put it to attemptToDelete queue may has better performance and more reasonable
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gb.WaitForNamedCacheSync(block until all queue in gb.monitor.controller synced there first batch)
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go wait.Until(gc.runAttemptToDeleteWorker, 1*time.Second, stopCh)
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gc.attemptToDelete.Get()
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gc.workerLock.RLock()
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gc.attemptToDeleteItem
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if item beingDeleted and has no dependents(children)
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pop — just pop since owner are pre executed before enqueue this node
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getObject from apiserver
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if not found or uid does not match
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dependencyGraphBuilder.enqueueVirtualDeleteEvent
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if deleting dependent
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attemptToDelete blockingDependents
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removeFinalizer if no blockingDependents
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classifyReferences
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patch ownerReference to delete solid owner
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detect circle reference
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do real deleteObject
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if err or not observed
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gc.attemptToDelete.AddRateLimited( put back to queue with ratelimit)
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go wait.Until(gc.runAttemptToOrphanWorker, 1*time.Second, stopCh)
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runAttemptToOrphanWorker
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orphanDependents remove owner children
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go garbageCollector.Sync(gcClientset.Discovery(), 30*time.Second, ctx.Stop)
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garbagecollector.NewDebugHandler(TODO)
possible PRs:
processGraphChanges. (PR return of this function is useless, doesn't exist in the graph Info should be warning)
gb.processTransitions — verify if it is being delete because reflector may combine create delete event into one event(PR: maybe this event should not be combined)
referencesDiffs — PR TODO: profile this function to see if a naive N^2 algorithm performs better when the number of references is small.
gb.attemptToDelete.Add(ownerNodes) — PR: check and update ownerNode dependents rather than put it to attemptToDelete queue may has better performance and more reasonable
// TODO: attemptToOrphanWorker() routine is similar. Consider merging
TODO: It's only necessary to talk to the API server if the owner node