Quick Answer
Sequential streams process elements one at a time in the current thread. Parallel streams split the work across multiple threads using the ForkJoinPool. Parallel can be faster for large datasets with CPU-intensive operations but adds overhead (splitting, merging, thread management). Parallel is harmful for: small collections, I/O operations, stateful operations, or when order matters with side effects.
Answer
Sequential streams process elements one-by-one. Parallel streams divide tasks into multiple threads. Parallelism improves performance for large datasets when operations are thread-safe.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
