What are the implementations of thread-safe lists available in standard libraries or popular libraries?

In Java, the following implementations exist for thread-safe lists:

• Collections.synchronizedList(List<T> list) — wraps a regular list in a synchronized version, where all methods are synchronized on an internal mutex. Easy to use, but requires external synchronization during iteration.

• CopyOnWriteArrayList (from java.util.concurrent) — a thread-safe list that creates a copy of the internal array upon modifications. Good for scenarios with many reads and infrequent modifications, as reading is not blocked.

• ConcurrentLinkedQueue — although this is a queue, not a list, it is sometimes used for thread-safe storage of elements with non-blocking access.

Example of using CopyOnWriteArrayList:

import java.util.concurrent.CopyOnWriteArrayList;

CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<>();
list.add("element1");
list.add("element2");

for (String s : list) {
    System.out.println(s);
}

Thus, the choice of implementation depends on performance requirements and the nature of operations (read/write).