博客
关于我
26. ForkJoin:单机版的MapReduce - 并发工具类
阅读量:386 次
发布时间:2019-03-05

本文共 2478 字,大约阅读时间需要 8 分钟。

???????ForkJoin??

??????

????????????????????????????????????????????????????????????????????????????

  • ??????????????????????????????????????
  • ??????????????????????????????
  • Fork/Join???

    Fork/Join???Java???????????????????????????????????????

    • Fork?????????fork()????????????????????
    • Join?????????join()?????????????????

    ForkJoin?????????????

  • ForkJoinPool????????????????ForkJoin???????????????????????????
  • ForkJoinTask???????????????????????????
    • fork()??????????
    • join()??????????????
  • ForkJoinTask????????

  • RecursiveAction?????????????????????????
  • RecursiveTask????????????????????????
  • ForkJoinPool????

    ForkJoinPool??????????-???????????????????????ForkJoinPool????????????????????????????????????????????????????????????????

    ForkJoinPool??????????????????????????????????

    ??MapReduce??????

    MapReduce???????????????????????????MapReduce??????????

    public class MyTest2 {    public static void main(String[] args) {        String[] fc = {            "hello world", "hello me", "hello fork", "hello join",            "fork join in world"        };        ForkJoinPool fjp = new ForkJoinPool(3);        MR mr = new MR(fc, 0, fc.length);        Map
    result = fjp.invoke(mr); result.forEach((k, v) -> System.out.println(k + ":" + v)); } static class MR extends RecursiveTask
    > { private String[] fc; private int start, end; MR(String[] fc, int fr, int to) { this.fc = fc; this.start = fr; this.end = to; } @Override protected Map
    compute() { if (end - start == 1) { return calc(fc[start]); } else { int mid = (start + end) / 2; MR mr1 = new MR(fc, start, mid); mr1.fork(); MR mr2 = new MR(fc, mid, end); return merge(mr2.compute(), mr1.join()); } } private Map
    merge(Map
    r1, Map
    r2) { Map
    result = new HashMap<>(); result.putAll(r1); r2.forEach((k, v) -> { Long c = result.get(k); if (c != null) { result.put(k, c + v); } else { result.put(k, v); } }); return result; } private Map
    calc(String line) { Map
    result = new HashMap<>(); String[] words = line.split("\\s+"); for (String w : words) { Long v = result.get(w); if (v != null) { result.put(w, v + 1L); } else { result.put(w, 1L); } } return result; } }}

    ??????MR???????????????????????ForkJoin?????????????????????????????????

    转载地址:http://hihwz.baihongyu.com/

    你可能感兴趣的文章
    mysqldump 参数--lock-tables浅析
    查看>>
    mysqldump 导出中文乱码
    查看>>
    mysqldump 导出数据库中每张表的前n条
    查看>>
    mysqldump: Got error: 1044: Access denied for user ‘xx’@’xx’ to database ‘xx’ when using LOCK TABLES
    查看>>
    Mysqldump参数大全(参数来源于mysql5.5.19源码)
    查看>>
    mysqldump备份时忽略某些表
    查看>>
    mysqldump实现数据备份及灾难恢复
    查看>>
    mysqldump数据库备份无法进行操作只能查询 --single-transaction
    查看>>
    mysqldump的一些用法
    查看>>
    mysqli
    查看>>
    MySQLIntegrityConstraintViolationException异常处理
    查看>>
    mysqlreport分析工具详解
    查看>>
    MySQLSyntaxErrorException: Unknown error 1146和SQLSyntaxErrorException: Unknown error 1146
    查看>>
    Mysql_Postgresql中_geometry数据操作_st_astext_GeomFromEWKT函数_在java中转换geometry的16进制数据---PostgreSQL工作笔记007
    查看>>
    mysql_real_connect 参数注意
    查看>>
    mysql_secure_installation初始化数据库报Access denied
    查看>>
    MySQL_西安11月销售昨日未上架的产品_20161212
    查看>>
    Mysql——深入浅出InnoDB底层原理
    查看>>
    MySQL“被动”性能优化汇总
    查看>>
    MySQL、HBase 和 Elasticsearch:特点与区别详解
    查看>>