Would this be better because synchronize lock would be held for a shorter period?
Yes, your suggested approach is better because it reduces the time the synchronized lock is held, improving concurrency. Here's why:
Advantages:
Shorter Lock Duration: The synchronized block is used only to create a copy of the SortedSet. Once the copy is made, the lock on sortedSet is released, allowing other threads to perform operations on the original set.
No Concurrent Modification During Iteration: By iterating over the copy (copyTreeSet), any concurrent modifications to the original sortedSet during iteration won't affect the loop or cause a ConcurrentModificationException.
Why This Is Better:
Reduced Contention: Threads modifying sortedSet are blocked for a shorter period (just enough to copy the elements).
Thread Safety Maintained: Synchronization ensures a consistent snapshot of the sortedSet at the time of copying.
Safe Iteration: Iterating over copyTreeSet avoids ConcurrentModificationException.
Considerations:
Memory Overhead: There’s a small overhead of creating a TreeSet copy, which might be significant if the set is very large.
Snapshot Consistency: The iteration represents a snapshot of the sortedSet at the moment of copying. Changes made to the original sortedSet after the copy won't be reflected in the iteration.
This
pattern is a good compromise between safety and performance. If modifications to the SortedSet during iteration are frequent and need to be visible, consider alternatives like ConcurrentSkipListSet.