// Execute concurrently
crawler1.setBackground(true);
crawler2.setBackground(true);

String sessionId1 = crawler1.execute();
String sessionId2 = crawler2.execute();

crawler1.awaitTermination();
crawler2.awaitTermination();
```

### Custom Interval Control

```java
// Configure politeness policy
container.singleton("intervalController", DefaultIntervalController.class, controller -> {

            assertEquals(CrawlerStatus.RUNNING, crawler1.crawlerContext.getStatus());
            assertEquals(CrawlerStatus.RUNNING, crawler2.crawlerContext.getStatus());

            crawler1.awaitTermination();
            crawler2.awaitTermination();

            assertEquals(maxCount, dataService.getCount(sessionId1));
            assertEquals(maxCount, dataService.getCount(sessionId2));

            UrlQueue urlQueue;

        parentThread.start();
        if (!background) {
            awaitTermination();
        }
        return crawlerContext.sessionId;
    }

    /**
     * Waits for the crawling process to terminate indefinitely.
     */
    public void awaitTermination() {
        awaitTermination(0);
    }

    /**
     * Waits for the crawling process to terminate for a specified duration.

                }
                Thread.sleep(50);
            }
            assertEquals(CrawlerStatus.RUNNING, crawler2.crawlerContext.getStatus());

            crawler1.awaitTermination();
            crawler2.awaitTermination();

            assertEquals(maxCount, dataService.getCount(sessionId1));
            assertEquals(maxCount, dataService.getCount(sessionId2));

            UrlQueue urlQueue;

            assertEquals(CrawlerStatus.RUNNING, crawler1.crawlerContext.getStatus());
            assertEquals(CrawlerStatus.RUNNING, crawler2.crawlerContext.getStatus());

            crawler1.awaitTermination();
            crawler2.awaitTermination();

            assertEquals(maxCount, dataService.getCount(sessionId1));
            assertEquals(maxCount, dataService.getCount(sessionId2));

            UrlQueue urlQueue;