crawler.setBackground(true);
String sessionId = crawler.execute();

// Check crawling status
while (crawler.crawlerContext.getStatus() == CrawlerStatus.RUNNING) {
    Thread.sleep(1000);
    System.out.println("Crawling in progress...");
}

// Wait for completion
crawler.awaitTermination();
System.out.println("Crawling completed");
```

### Custom Content Extractor

```java

        statusMap.put(CrawlerStatus.RUNNING, "In progress");
        statusMap.put(CrawlerStatus.DONE, "Completed");

        // Verify entries
        assertEquals(3, statusMap.size());
        assertEquals("Starting up", statusMap.get(CrawlerStatus.INITIALIZING));
        assertEquals("In progress", statusMap.get(CrawlerStatus.RUNNING));

        // Start crawling
        crawlerContext.setStatus(CrawlerStatus.RUNNING);
        crawlerContext.setActiveThreadCount(5);

        // Simulate crawling progress
        for (int i = 0; i < 100; i++) {
            crawlerContext.incrementAndGetAccessCount();
            crawlerContext.getRobotsTxtUrlSet().add("http://site" + i + ".com/robots.txt");
        }