[jonathanlydall]

What about spotting a cycle by using an incrementing counter and then throwing an exception if it goes above the tree depth or collection size (presuming one of these is tracked)?

Unlike the author’s hash set proposal it would require almost no memory or CPU overhead and may be more likely to be accepted.

That being said, in the decade plus I’ve used C# I’ve never found that I failed to consider concurrent access on data structures in concurrent situations.

[saagarjha]

It’s not a horrible idea but adding useful preconditions in the face of data races is quite hard in general. This is just one of the ways the tree can break.

[exDM69]

Yes, this is a good idea. I've done this before with binary search and tree structures. I avoid unbounded loops wherever possible and the unavoidable cases are rather rare.

It's not a fix but it is a good mitigation strategy.

Infinite loops are one of the nastiest kind of bugs. Although they are easy to spot in a debugger they can have really unfriendly consequences like OP's "can barely ssh in" situation.

Infinite loops in library code are particularly unpleasant.

[TYMorningCoffee]

That's much better. Constant memory. The number of nodes is guaranteed to be less than or equal to the height of the tree.