flink算子类在多个subtask中是各自初始化1个实例对象吗？

Hi，all：

flink算子在多个并行度的job中，每个算子（假如1个算子都有一个对应的java类）在多个subtask中会共享1个java类实例吗？还是每个subtask都会各自的实例？

我做了一个简单测试，写了一个flatmap类，在构造方法和open方法中打印类的toString方法，发现输出都不同，是否可以证明每个subtask都初始化了自己的类实例？

希望有朋友能解释下算子在job运行中初始化的过程。

测试相关代码如下：

// flink 1.10.2版本，并行度为3 @Slf4j public class PersonFlatMap extends RichFlatMapFunction<Tuple2<String, String>, Person> { private transient ValueState state;

public PersonFlatMap(){ log.info(String.format("PersonFlatMap【%s】: 创建实例",this.toString())); }

@Override public void open(Configuration parameters) throws IOException { //略去无关代码... log.info(String.format("PersonFlatMap【%s】:初始化状态!", this.toString())); }

@Override

public void flatMap(Tuple2<String, String> t, Collector collector) throws Exception { Person p = JSONUtil.toObject(t.f1,Person.class); collector.collect(p); if(state.value() == null){state.update(0);} state.update(state.value() + 1); log.info("state: "+state.value()); } }

//测试日志输出 ... flink-10.2 - [2020-11-16 13:41:54.360] - INFO [main] com.toonyoo.operator.PersonFlatMap - PersonFlatMap【com.toonyoo.operator.PersonFlatMap@ba8d91c】: 创建实例

//此处略去无关日志...

flink-10.2 - [2020-11-16 13:42:00.326] - INFO [Flat Map -> Sink: Print to Std. Out (1/3)] org.apache.flink.runtime.state.heap.HeapKeyedStateBackend - Initializing heap keyed state backend with stream factory. flink-10.2 - [2020-11-16 13:42:00.351] - INFO [Flat Map -> Sink: Print to Std. Out (1/3)] com.toonyoo.operator.PersonFlatMap - PersonFlatMap【com.toonyoo.operator.PersonFlatMap@5c9d895d】:初始化状态! flink-10.2 - [2020-11-16 13:42:00.354] - INFO [Flat Map -> Sink: Print to Std. Out (3/3)] com.toonyoo.operator.PersonFlatMap - PersonFlatMap【com.toonyoo.operator.PersonFlatMap@5c489c40】:初始化状态! flink-10.2 - [2020-11-16 13:42:00.356] - INFO [Flat Map -> Sink: Print to Std. Out (2/3)] com.toonyoo.operator.PersonFlatMap - PersonFlatMap【com.toonyoo.operator.PersonFlatMap@1cd4f5c9】:初始化状态! ...*来自志愿者整理的flink邮件归档