[Question] list_set doesn't terminate in concurrent tests

[buttercrab]

I passed all the sequential tests.
However in concurrent tests, I failed due to timeout.
I think the only way that the program doesn't terminate is deadlock.
However, is it possible to have deadlock?
My algorithm runs like this on insert or remove:

1. Look at head (with lock)
2. If we should go to next node, we get a lock and drop the lock on head.
3. At the end when we insert or remove the node, we hold the lock of node before and after.

[Lee-Janggun]

For 3, are you trying to hold two additional locks in addition to the one you got in the one in self.find()?