Java Parallel Streams Internals: Non-Concurrent & Concurrent Collectors (Part 1)

This video discusses the intricacies of non-concurrent and concurrent collectors in Java, particularly in the context of parallel streams. Non-concurrent collectors partition inputs into chunks that are processed in parallel but then require merging into a single result container, all without needing explicit synchronization. Concurrent collectors, on the other hand, use a single mutable result container, often a concurrent collection like ConcurrentHashMap, to which multiple threads write concurrently. The choice between the two is performance-driven: concurrent collectors may be more efficient for data types like maps and sets where merging costs are high but may not preserve element order.