final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
String file = "file:/path/events.txt";
DataSet<Tuple5<String,String,String,String, Double>> csvInput = env.readCsvFile(file)
               .types(String.class,String.class,String.class,String.class, Double.class);
            
csvInput.groupBy(2)
.sortGroup(3, Order.ASCENDING)
.sortGroup(1, Order.DESCENDING)        
.combineGroup(new MyGroupCombineFunction())
.print();
// .writeAsCsv("file:///path/events_result",WriteMode.OVERWRITE);


使用 print 可正常输出
改成 writeAsCsv 后 一运行就结束了

注意
一定要 调用 env.execute() 才会运行