为什么更新广播变量示例代码无效？

Question

我想每分钟更新一次广播变量。因此，在这个问题中，我将使用Aastha提供的示例代码。 how can I update a broadcast variable in Spark streaming?

但是没有用。函数updateAndGet()仅在流应用程序启动时起作用。当我调试代码时，它没有两次进入功能updateAndGet()。因此，广播变量不会每分钟更新一次。

为什么？

这是我的示例代码。

public class BroadcastWrapper {

private Broadcast<List<String>> broadcastVar;
private Date lastUpdatedAt = Calendar.getInstance().getTime();

private static BroadcastWrapper obj = new BroadcastWrapper();

private BroadcastWrapper(){}

public static BroadcastWrapper getInstance() {
    return obj;
}

public JavaSparkContext getSparkContext(SparkContext sc) {
   JavaSparkContext jsc = JavaSparkContext.fromSparkContext(sc);
   return jsc;
}

public Broadcast<List<String>> updateAndGet(JavaStreamingContext jsc) {
    Date currentDate = Calendar.getInstance().getTime();
    long diff = currentDate.getTime()-lastUpdatedAt.getTime();
    if (broadcastVar == null || diff > 60000) { // Lets say we want to refresh every 1 min =
                                                // 60000 ms
        if (broadcastVar != null)
            broadcastVar.unpersist();
        lastUpdatedAt = new Date(System.currentTimeMillis());

        // Your logic to refreshs
        // List<String> data = getRefData();
        List<String> data = new ArrayList<String>();
        data.add("tang");
        data.add("xiao");
        data.add(String.valueOf(System.currentTimeMillis()));

        broadcastVar = jsc.sparkContext().broadcast(data);
   }
    return broadcastVar;}}




//Here is the computing code submit to spark streaming.

lines.transform(new Function<JavaRDD<String>, JavaRDD<String>>() {
Broadcast<List<String>> blacklist =
        BroadcastWrapper.getInstance().updateAndGet(jsc);
@Override
public JavaRDD<String> call(JavaRDD<String> rdd) {
    JavaRDD<String> dd=rdd.filter(new Function<String, Boolean>() {
        @Override
        public Boolean call(String word) {
            if (blacklist.getValue().contains(word)) {
                return false;
            } else {
                return true;
            }
        }
    });
    return dd;
}});