void (boolean headless) { System.setProperty("java.util.concurrent.ForkJoinPool.common.threadFactory", IdeaForkJoinWorkerThreadFactory.class.getName()); boolean parallelismWasNotSpecified = System.getProperty("java.util.concurrent.ForkJoinPool.common.parallelism") == null; if (parallelismWasNotSpecified) { int N_CPU = Runtime.getRuntime().availableProcessors(); // By default, FJP initialized with the parallelism=N_CPU - 1 // so in case of two processors it becomes parallelism=1 which is too unexpected. // In this case force parallelism=2 // In case of headless execution (unit tests or inspection command-line) there is no AWT thread to reserve cycles for, so dedicate all CPUs for FJP if (headless || N_CPU == 2) { System.setProperty("java.util.concurrent.ForkJoinPool.common.parallelism", String.valueOf(N_CPU)); } } }