parallelStream() runs on the common pool, which your whole JVM shares

There is one ForkJoinPool.commonPool per JVM and its parallelism is cpus - 1. One long parallel stream starves every other parallel stream in the process, including ones inside libraries you did not write.

Full code & output

This topic is available to PRO members.

Sign in Create a free account

Run this yourself in the Online Java Compiler, spin up a live REST API in the API Sandbox, or practise with Java interview questions.

Published 2026-08-25