Changes between Initial Version and Version 1 of waue/2010/0115

Timestamp:

Jan 19, 2010, 4:28:47 PM (14 years ago)

Author:

waue

Comment:

--

waue/2010/0115

@@ +1 @@
+ = 將 wordcount2 改成 0.20 版 =
+
+ == 前言 ==
+按照hadoop 0.20 官方網頁的 wordcount v2 .
+[[http://hadoop.apache.org/common/docs/r0.20.1/mapred_tutorial.html#Example%3A+WordCount+v1.0 ]]
+
+最需要給的地方是 ''' " extends MapReduceBase implements Mapper" ''' 原因是在hadoop 0.20時，mapreducebase 此class已經被deprecated，
+
+因此應改寫如 ''' " extends Mapper" '''
+
+然而最主要不能改變的原因是，程式中很重要的功能 [http://hadoop.apache.org/common/docs/r0.20.1/api/org/apache/hadoop/filecache/DistributedCache.html DistributedCache ]  以及 -Dwordcount.skip.patterns 等功能寫於 configure() 函數內。 此configure() 繼承自 MapReduceBase，
+
+因此若整個程式改成hadoop 0.20 的 " extends Mapper" '''，則有些功能將不知是否能使用
+
+
+ == 原始程式碼 ==
+
+{{{
+#!java
+public class WordCountV2 extends Configured implements Tool {
+
+        public static class Map extends MapReduceBase implements
+                        Mapper<LongWritable, Text, Text, IntWritable> {
+
+                static enum Counters {
+                        INPUT_WORDS
+                }
+
+                private final static IntWritable one = new IntWritable(1);
+                private Text word = new Text();
+
+                private boolean caseSensitive = true;
+                private Set<String> patternsToSkip = new HashSet<String>();
+
+                private long numRecords = 0;
+                private String inputFile;
+
+                public void configure(JobConf job) {
+                        caseSensitive = job.getBoolean("wordcount.case.sensitive", true);
+                        inputFile = job.get("map.input.file");
+
+                        if (job.getBoolean("wordcount.skip.patterns", false)) {
+                                Path[] patternsFiles = new Path[0];
+                                try {
+                                        patternsFiles = DistributedCache.getLocalCacheFiles(job);
+                                } catch (IOException ioe) {
+                                        System.err
+                                                        .println("Caught exception while getting cached files: "
+                                                                        + StringUtils.stringifyException(ioe));
+                                }
+                                for (Path patternsFile : patternsFiles) {
+                                        parseSkipFile(patternsFile);
+                                }
+                        }
+                }
+
+                private void parseSkipFile(Path patternsFile) {
+                        try {
+                                BufferedReader fis = new BufferedReader(new FileReader(
+                                                patternsFile.toString()));
+                                String pattern = null;
+                                while ((pattern = fis.readLine()) != null) {
+                                        patternsToSkip.add(pattern);
+                                }
+                        } catch (IOException ioe) {
+                                System.err
+                                                .println("Caught exception while parsing the cached file '"
+                                                                + patternsFile
+                                                                + "' : "
+                                                                + StringUtils.stringifyException(ioe));
+                        }
+                }
+
+                public void map(LongWritable key, Text value,
+                                OutputCollector<Text, IntWritable> output, Reporter reporter)
+                                throws IOException {
+                        String line = (caseSensitive) ? value.toString() : value.toString()
+                                        .toLowerCase();
+
+                        for (String pattern : patternsToSkip) {
+                                line = line.replaceAll(pattern, "");
+                        }
+
+                        StringTokenizer tokenizer = new StringTokenizer(line);
+                        while (tokenizer.hasMoreTokens()) {
+                                word.set(tokenizer.nextToken());
+                                output.collect(word, one);
+                                reporter.incrCounter(Counters.INPUT_WORDS, 1);
+                        }
+
+                        if ((++numRecords % 100) == 0) {
+                                reporter.setStatus("Finished processing " + numRecords
+                                                + " records " + "from the input file: " + inputFile);
+                        }
+                }
+        }
+
+        public static class Reduce extends MapReduceBase implements
+                        Reducer<Text, IntWritable, Text, IntWritable> {
+                public void reduce(Text key, Iterator<IntWritable> values,
+                                OutputCollector<Text, IntWritable> output, Reporter reporter)
+                                throws IOException {
+                        int sum = 0;
+                        while (values.hasNext()) {
+                                sum += values.next().get();
+                        }
+                        output.collect(key, new IntWritable(sum));
+                }
+        }
+
+        public int run(String[] args) throws Exception {
+
+
+                JobConf conf = new JobConf(getConf(), WordCount.class);
+                conf.setJobName("wordcount");
+
+                conf.setOutputKeyClass(Text.class);
+                conf.setOutputValueClass(IntWritable.class);
+
+                conf.setMapperClass(Map.class);
+                conf.setCombinerClass(Reduce.class);
+                conf.setReducerClass(Reduce.class);
+
+                conf.setInputFormat(TextInputFormat.class);
+                conf.setOutputFormat(TextOutputFormat.class);
+
+                List<String> other_args = new ArrayList<String>();
+                for (int i = 0; i < args.length; ++i) {
+                        if ("-skip".equals(args[i])) {
+                                DistributedCache
+                                                .addCacheFile(new Path(args[++i]).toUri(), conf);
+                                conf.setBoolean("wordcount.skip.patterns", true);
+                        } else {
+                                other_args.add(args[i]);
+                        }
+                }
+
+                FileInputFormat.setInputPaths(conf, new Path(other_args.get(0)));
+                FileOutputFormat.setOutputPath(conf, new Path(other_args.get(1)));
+                CheckAndDelete.checkAndDelete(other_args.get(1), conf);
+                JobClient.runJob(conf);
+                return 0;
+        }
+
+        public static void main(String[] args) throws Exception {
+                String[] argv = { "-Dwordcount.case.sensitive=false",
+                                "/user/waue/input", "/user/waue/output-wc2", "-skip",
+                                "/user/waue/patterns/patterns.txt" };
+                args = argv;
+                int res = ToolRunner.run(new Configuration(), new WordCountV2(), args);
+                System.exit(res);
+        }
+}
+}}}
+
+ == 原始程式碼 ==