testScaleUpDoesNotExceedMaxThreads() — netty Function Reference

Source Code

common/src/test/java/io/netty/util/concurrent/AutoScalingEventExecutorChooserFactoryTest.java lines 197–243

    @Test
    @Timeout(30)
    void testScaleUpDoesNotExceedMaxThreads() throws Exception {
        TestEventExecutorGroup group = new TestEventExecutorGroup(1, 2, 50, TimeUnit.MILLISECONDS);
        try {
            startAllExecutors(group);
            Thread.sleep(200); // Allow time for initial scale-down to minThreads
            assertEquals(1, group.activeExecutorCount());

            TestEventExecutor activeExecutor = null;
            for (EventExecutor exec : group) {
                if (!exec.isSuspended()) {
                    activeExecutor = (TestEventExecutor) exec;
                    break;
                }
            }
            if (activeExecutor == null) {
                fail("Could not find an active executor to stress.");
            }
            activeExecutor.setHighLoad(true);

            // Wait for the UtilizationMonitor to react and scale up.
            long deadline = System.nanoTime() + TimeUnit.SECONDS.toNanos(5);
            while (group.activeExecutorCount() < 2 && System.nanoTime() < deadline) {
                Thread.sleep(50);
            }
            assertEquals(2, group.activeExecutorCount(), "Should scale up to maxThreads");

            // Now that we have scaled up, put all active executors under a high load
            // to prevent the new one from being scaled back down immediately.
            for (EventExecutor exec : group) {
                if (!exec.isSuspended()) {
                    ((TestEventExecutor) exec).setHighLoad(true);
                }
            }

            // Further calls to next() should not increase the count, and the group should
            // remain at its max size because both threads are now busy.
            group.next();
            Thread.sleep(200); // Give the monitor time to check again.

            assertEquals(2, group.activeExecutorCount(),
                         "Should not scale back down while load is high");
        } finally {
            group.shutdownGracefully().syncUninterruptibly();
        }
    }