Flink教程-快速开始

Flink教程-快速开始

Apache Flink 是一个开源的分布式批数据以及流数据处理平台。目前已经升级为 Apache 顶级开源项目。不管是 Spark 仍是 Flink，他们的主要优点都是基于内存运行机器学习算法，运行速度很是快，并且 Flink 支持迭代计算。做为大数据挖掘工程师两个工具都必须掌握。
Flink 刚刚开源，国内关注人数不是不少，源代码量也不大，可是看 Spark 的源码就有点困难了，因此学习 Flink，也能学习到一个优秀的分布式框架是怎么样一步一步构建起来的。

Flink安装准备

Flink运行支持 Linux、苹果、Windows 主流平台。不过最好仍是使用 Linux。下面给出安装前的准备：

1. 安装 Jdk1.7.X 或者以上的版本
2. 在 Flink 官网下载对应 Hadoop 预编译版本

将预编译版本解压，进入解压缩文件，为了方便，后文统一称此目录为：FLINK_HOME。

开始安装

单机快速尝试

单机尝试很是简单，直接执行命令：

1. Linux用户： sh bin/start-local.sh
2. Windows用户，在命令窗户输入：bin\start-local.bat

等待其出现以下提示以后：

D:\Java\flink\flink-0.10.1>bin\start-local.bat
Starting Flink job manager. Webinterface by default on http://localhost:8081/.
Don't close this batch window. Stop job manager by pressing Ctrl+C.

在浏览器中输入：http://localhost:8081/，Flink默认监听8081端口，防止其余进程占用此端口。此时出现下面的管理界面：

能够发现这个界面和 Spark 的管理界面的逻辑差很少，主要是管理正在运行的Job，已经完成的 Job，以及Task 管理和 Job 管理，Task 应该是管理 Job 的，之后再仔细分析里面的逻辑。

跑第一个例子

下面火烧眉毛先来跑一个分布式系统最经典的例子：WordCount，下面以 FLINK_HOME 的 README.txt 文件做为示例文件，测试 WordCount 程序，在 Windows 上面运行代码以及运行过程以下图：

D:\Java\flink\flink-0.10.1>bin\flink.bat run .\examples\WordCount.jar file:/D:/Java/flink/flink-0.10.1/README.txt file:/D:/Java/flink/flink-0.10.1/wordcount-result.txt
log4j:WARN No appenders could be found for logger (org.apache.hadoop.metrics2.li
b.MutableMetricsFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
01/15/2016 16:30:51     Job execution switched to status RUNNING.
01/15/2016 16:30:51     CHAIN DataSource (at getTextDataSet(WordCount.java:142)
(org.apache.flink.api.java.io.TextInputFormat)) -> FlatMap (FlatMap at main(WordCount.java:69)) -> Combine(SUM(1), at main(WordCount.java:72)(1/1) switched to SCHEDULED
01/15/2016 16:30:51     CHAIN DataSource (at getTextDataSet(WordCount.java:142)
(org.apache.flink.api.java.io.TextInputFormat)) -> FlatMap (FlatMap at main(WordCount.java:69)) -> Combine(SUM(1), at main(WordCount.java:72)(1/1) switched to DEPLOYING
01/15/2016 16:30:52     CHAIN DataSource (at getTextDataSet(WordCount.java:142)
(org.apache.flink.api.java.io.TextInputFormat)) -> FlatMap (FlatMap at main(WordCount.java:69)) -> Combine(SUM(1), at main(WordCount.java:72)(1/1) switched to RUNNING
01/15/2016 16:30:52     Reduce (SUM(1), at main(WordCount.java:72)(1/1) switched to SCHEDULED
01/15/2016 16:30:52     Reduce (SUM(1), at main(WordCount.java:72)(1/1) switched to DEPLOYING
01/15/2016 16:30:52     CHAIN DataSource (at getTextDataSet(WordCount.java:142)
(org.apache.flink.api.java.io.TextInputFormat)) -> FlatMap (FlatMap at main(WordCount.java:69)) -> Combine(SUM(1), at main(WordCount.java:72)(1/1) switched to FINISHED
01/15/2016 16:30:52     Reduce (SUM(1), at main(WordCount.java:72)(1/1) switched to RUNNING
01/15/2016 16:30:53     DataSink (CsvOutputFormat (path: file:/D:/Java/flink/flink-0.10.1/wordcount-result.txt, delimiter:  ))(1/1) switched to SCHEDULED
01/15/2016 16:30:53     DataSink (CsvOutputFormat (path: file:/D:/Java/flink/flink-0.10.1/wordcount-result.txt, delimiter:  ))(1/1) switched to DEPLOYING
01/15/2016 16:30:53     Reduce (SUM(1), at main(WordCount.java:72)(1/1) switched to FINISHED
01/15/2016 16:30:53     DataSink (CsvOutputFormat (path: file:/D:/Java/flink/flink-0.10.1/wordcount-result.txt, delimiter:  ))(1/1) switched to RUNNING
01/15/2016 16:30:53     DataSink (CsvOutputFormat (path: file:/D:/Java/flink/flink-0.10.1/wordcount-result.txt, delimiter:  ))(1/1) switched to FINISHED
01/15/2016 16:30:53     Job execution switched to status FINISHED.

能够看到输出日志很是详细，很方便就清楚整个运行流程，获得输出文件 wordcount-result.txt 前面10条内容以下 ：

1 1
13 1
5d002 1
740 1
about 1
account 1
administration 1
algorithms 1
and 7
another 1
any 2

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