assertEquals(10000, urlSet.size());
        assertTrue(urlSet.contains("http://overflow.com/robots.txt"));
        assertFalse(urlSet.contains("http://example0.com/robots.txt")); // First one should be evicted
    }

    /**
     * Test activeThreadCountLock getter
     */
    public void test_activeThreadCountLock() {
        Object lock = crawlerContext.getActiveThreadCountLock();
        assertNotNull(lock);

                urlQueue.setSessionId(sessionId);
                targetList.add(urlQueue);
            } else if (logger.isDebugEnabled()) {
                logger.debug("Existed URL: Session ID: {}, UrlQueue: {}", sessionId, urlQueue);
            }
        }
        if (!targetList.isEmpty()) {
            insertAll(targetList.stream()