conventional_thread_wait.java

void runConventional() throws Exception {
        for (; ; ) {
            long start = System.currentTimeMillis();
            try (var executor = Executors.newFixedThreadPool(1000)) {
                for (int i = 0; i < 100_000_0; i++) {
                    executor.submit(() -> {
                        callExternalService();
                        return null;
                    });
                }
            }
            long end = System.currentTimeMillis();
            System.out.println(end - start + " ms");
        }
    }
    
     private void callExternalService() throws InterruptedException {
        Thread.sleep(Duration.ofMillis(1));
    }