Is ConcurrentDictionary.GetOrAdd() guaranteed to invoke valueFactoryMethod only once per key?

Question

Problem: I need to implement object cache. The cache need to be thread-safe and need to populate values on demand(lazy loading). The values are retrieved vi

Answer 1

Is value factory invoked only once per key?

No, it isn't. The docs say:

If you call GetOrAdd simultaneously on different threads, valueFactory may be invoked multiple times, but its key/value pair might not be added to the dictionary for every call.