Apache Flink（集群中的標准輸出錯誤）

Question

在Apache Flink ，我無法在std out看到輸出，但我的工作正在成功運行並且數據即將到來

Answer 1

當您在集群上運行您的作業時，DataStreams 被打印到 TaskManager 進程的標准輸出。 這個 TaskManager stdout 被定向到 Flink 根目錄的 ./log/ 目錄中的一個 .out 文件。 我相信這是在這里您已經看到了您的輸出。

我不知道是否可以更改 TaskManagers 的標准輸出，但是，一個快速而骯臟的解決方案可能是將輸出寫入套接字：

output.writeToSocket(outputHost, outputPort, new SimpleStringSchema())

Answer 2

public static void main(String[] args) throws Exception {

    // the host and the port to connect to
    final String hostname = "192.168.1.73";
    final int port = 9000;

    final StreamExecutionEnvironment env = StreamExecutionEnvironment.createRemoteEnvironment("192.168.1.68", 6123);

    // get input data by connecting to the socket
    DataStream<String> text = env.socketTextStream(hostname, port, "\n");

    // parse the data, group it, window it, and aggregate the counts
    DataStream<WordWithCount> windowCounts = text

            .flatMap(new FlatMapFunction<String, WordWithCount>() {
                public void flatMap(String value, Collector<WordWithCount> out) {
                    for (String word : value.split("\\s")) {
                        out.collect(new WordWithCount(word, 1L));
                    }
                }
            })

            .keyBy("word").timeWindow(Time.seconds(5))

            .reduce(new ReduceFunction<WordWithCount>() {
                public WordWithCount reduce(WordWithCount a, WordWithCount b) {
                    return new WordWithCount(a.word, a.count + b.count);
                }
            });

    // print the results with a single thread, rather than in parallel
    windowCounts.print().setParallelism(1);

    env.execute("Socket Window WordCount");
}

public static class WordWithCount {

    public String word;
    public long count;

    public WordWithCount() {
    }

    public WordWithCount(String word, long count) {
        this.word = word;
        this.count = count;
    }

    @Override
    public String toString() {
        return word + " : " + count;
    }
}