Java Apache Flink进程函数状态未保持该状态
我正在为Apache Flink 1.4中的processElement函数编写一些代码:Java Apache Flink进程函数状态未保持该状态,java,stream,apache-flink,flink-streaming,Java,Stream,Apache Flink,Flink Streaming,我正在为Apache Flink 1.4中的processElement函数编写一些代码: public class ProcessFunctionClass extends ProcessFunction<Tuple2<String, String>, Tuple2<String, String>>{ private ListState<String> listState; public void processElement
public class ProcessFunctionClass extends ProcessFunction<Tuple2<String, String>, Tuple2<String, String>>{
private ListState<String> listState;
public void processElement(Tuple2<String, String> tuple2, Context context, Collector<Tuple2<String, String>> collector) {
// if the state is empty, start a timer
if (listState.get().iterator().hasNext() == false)
context.timerService().registerEventTimeTimer(10000);
listState.add("someStringToBeStored");
// ...
}
}
当计时器过期时,我有此功能:
public void onTimer(long timestamp, OnTimerContext ctx, Collector<Tuple2<String, String>> out) throws Exception {
Iterable<String> strings = listState.get();
int cnt = 0;
int totalLength = 0;
Iterator<String> it = strings.iterator();
while (it.hasNext()) {
cnt++;
totalLength += it.next().length();
}
LOGGER.info("cnt is:" + cnt);
LOGGER.info("totalLength is:" + totalLength);
// clearing the state
listState.clear();
}
但是,每次运行应用程序时,cnt的值总是1,totalLength的值是当时已处理的特定字符串的长度。系统中似乎没有保存该状态。从这段代码可以清楚地看出我做错了什么吗?您的ProcessFunction类需要扩展Flink ProcessFunction。进程函数使用键分区状态,这意味着每个键都有一个单独的列表。我的猜测是,没有一个键在10秒内有多个事件。是的,我忘记把它放在这里了。编辑。