When is it better not to use parallelStream?.

It is not recommended to use parallelStream in the following cases:

• When the operations inside the stream are not thread-safe or have side effects.
• If the data volume is small — the overhead of creating threads may outweigh the benefits.
• When working with data sources that do not parallelize well (e.g., LinkedList).
• If the order of processing elements is important and must be strictly maintained.
• In environments with limited resources, where parallelism can lead to performance degradation.

Example: if you have a sequence of operations that modify a shared object without synchronization, using parallelStream can lead to errors.