🐛 set partialmetadata gvk in list/watch funcs to avoid data race in cache #1650
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…n cache Signed-off-by: Joe Lanford <joe.lanford@gmail.com>
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What exactly races there? |
With just the added test, the race detector shows this: Race detector details
TL;DR: it's multiple goroutines (one from each controller) trying to call SetGroupVersionKind on the same underlying object concurrently. |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: alvaroaleman, joelanford The full list of commands accepted by this bot can be found here. The pull request process is described here
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| func newGVKFixupWatcher(gvk schema.GroupVersionKind, watcher watch.Interface) watch.Interface { | ||
| ch := make(chan watch.Event) | ||
| w := &gvkFixupWatcher{ | ||
| gvk: gvk, | ||
| watcher: watcher, | ||
| ch: ch, | ||
| } | ||
| w.wg.Add(1) | ||
| go w.run() | ||
| return w | ||
| } | ||
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| func (w *gvkFixupWatcher) run() { | ||
| for e := range w.watcher.ResultChan() { | ||
| e.Object.GetObjectKind().SetGroupVersionKind(w.gvk) | ||
| w.ch <- e | ||
| } | ||
| w.wg.Done() | ||
| } | ||
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| func (w *gvkFixupWatcher) Stop() { | ||
| w.watcher.Stop() | ||
| w.wg.Wait() | ||
| close(w.ch) | ||
| } | ||
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| func (w *gvkFixupWatcher) ResultChan() <-chan watch.Event { | ||
| return w.ch | ||
| } |
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Is this the only way we can fix this behavior? Having an extra reader seems a bit overkill, given that's a reader on a reader, but I also don't have other options that I can think about.
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When multiple controllers are watching the same resource type with a metadata-only informer, a data race occurs in
sigs.k8s.io/controller-runtime/pkg/cache/internal.(*handlerPreserveGVK).resetGroupVersionKind()This data race is resolved by setting the GVK before the objects are written to the cache.
Signed-off-by: Joe Lanford joe.lanford@gmail.com