@Test
    public void appendNodeHistogram() throws InterruptedException {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(16);
        executor.setMaxPoolSize(16);
        executor.setQueueCapacity(1024);

        int maxCount = 100;
        @SuppressWarnings("unchecked")
        CompletableFuture<String>[] array = new CompletableFuture[maxCount];
        AtomicBoolean timeout = new AtomicBoolean(false);
        for (int i = 0; i < maxCount; i++) {
            array[i] = makeCompletableFuture(i, timeout);
        }

        CompletableFuture<Void> completableFuture = CompletableFuture.allOf(array);
        try {
            completableFuture.get(100, TimeUnit.MILLISECONDS);
        } catch (Exception e) {
            timeout.set(Boolean.TRUE);
        }
        TimeUnit.SECONDS.sleep(3);
        logger.debug("END");
    }
Checks histograms for user node.
<pre>
    userNode ---> wasNode (2 agents)
</pre>
web/src/test/java/com/navercorp/pinpoint/web/applicationmap/appender/histogram/NodeHistogramAppenderTest.java