Thread synchronization methods and apparatus for managed run-time environments are disclosed. An example method disclosed herein comprises determining a set of locking operations to perform on a lock corresponding to an object, performing an initial locking operation comprising at least one of a balanced synchronization of the lock and an optimistically balanced synchronization of the lock if the initial locking operation is not unbalanced, and, if the initial locking operation is active and comprises the optimistically balanced synchronization, further comprising modifying a state of a pending optimistically balanced release corresponding to the optimistically balanced synchronization if a subsequent locking operation is unbalanced.