hadoop - 为什么map/reduce输出一个空文件，没有报异常

Question

我实现了一个简单的 map/reduce 程序来创建一个倒排索引（我的小型搜索引擎的一部分）。每件事都工作得很好。但是在我将输入文件大小扩大到 20MB 以上（仍然是小文件进行测试）后，输出文件将为空。这意味着我可以找到文件“part-00000”，但它是 0 字节。

奇怪的是根本没有例外。这是我的日志:

（注意“映射输入记录=19405，组合输出记录=4111513，减少输入记录=0”）

SEInvertedIndex Program starts!...
12/10/28 00:58:05 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
12/10/28 00:58:05 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
12/10/28 00:58:05 WARN mapred.JobClient: No job jar file set.  User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
12/10/28 00:58:05 WARN snappy.LoadSnappy: Snappy native library not loaded
12/10/28 00:58:05 INFO mapred.FileInputFormat: Total input paths to process : 1
12/10/28 00:58:05 INFO mapred.JobClient: Running job: job_local_0001
12/10/28 00:58:05 INFO util.ProcessTree: setsid exited with exit code 0
12/10/28 00:58:05 INFO mapred.Task:  Using ResourceCalculatorPlugin : org.apache.hadoop.util.LinuxResourceCalculatorPlugin@8c4a77
12/10/28 00:58:05 INFO mapred.MapTask: numReduceTasks: 1
12/10/28 00:58:05 INFO mapred.MapTask: io.sort.mb = 100
12/10/28 00:58:05 INFO mapred.MapTask: data buffer = 79691776/99614720
12/10/28 00:58:05 INFO mapred.MapTask: record buffer = 262144/327680
12/10/28 00:58:06 INFO mapred.JobClient:  map 0% reduce 0%
12/10/28 00:58:08 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:08 INFO mapred.MapTask: bufstart = 0; bufend = 25657705; bufvoid = 99614720
12/10/28 00:58:08 INFO mapred.MapTask: kvstart = 0; kvend = 262144; length = 327680
12/10/28 00:58:10 INFO mapred.MapTask: Finished spill 0
12/10/28 00:58:11 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:11 INFO mapred.MapTask: bufstart = 25657705; bufend = 55385370; bufvoid = 99614720
12/10/28 00:58:11 INFO mapred.MapTask: kvstart = 262144; kvend = 196607; length = 327680
12/10/28 00:58:11 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:12 INFO mapred.JobClient:  map 5% reduce 0%
12/10/28 00:58:12 INFO mapred.MapTask: Finished spill 1
12/10/28 00:58:13 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:13 INFO mapred.MapTask: bufstart = 55385370; bufend = 87701074; bufvoid = 99614720
12/10/28 00:58:13 INFO mapred.MapTask: kvstart = 196607; kvend = 131070; length = 327680
12/10/28 00:58:14 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:14 INFO mapred.MapTask: Finished spill 2
12/10/28 00:58:15 INFO mapred.JobClient:  map 8% reduce 0%
12/10/28 00:58:15 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:15 INFO mapred.MapTask: bufstart = 87701074; bufend = 17642207; bufvoid = 99614622
12/10/28 00:58:15 INFO mapred.MapTask: kvstart = 131070; kvend = 65533; length = 327680
12/10/28 00:58:17 INFO mapred.MapTask: Finished spill 3
12/10/28 00:58:17 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:17 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:17 INFO mapred.MapTask: bufstart = 17642207; bufend = 47171716; bufvoid = 99614720
12/10/28 00:58:17 INFO mapred.MapTask: kvstart = 65533; kvend = 327677; length = 327680
12/10/28 00:58:18 INFO mapred.JobClient:  map 12% reduce 0%
12/10/28 00:58:19 INFO mapred.MapTask: Finished spill 4
12/10/28 00:58:20 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:20 INFO mapred.MapTask: bufstart = 47171716; bufend = 75047441; bufvoid = 99614720
12/10/28 00:58:20 INFO mapred.MapTask: kvstart = 327677; kvend = 262140; length = 327680
12/10/28 00:58:20 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:21 INFO mapred.JobClient:  map 16% reduce 0%
12/10/28 00:58:21 INFO mapred.MapTask: Finished spill 5
12/10/28 00:58:22 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:22 INFO mapred.MapTask: bufstart = 75047441; bufend = 7640048; bufvoid = 99614657
12/10/28 00:58:22 INFO mapred.MapTask: kvstart = 262140; kvend = 196603; length = 327680
12/10/28 00:58:23 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:24 INFO mapred.MapTask: Finished spill 6
12/10/28 00:58:24 INFO mapred.JobClient:  map 19% reduce 0%
12/10/28 00:58:24 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:24 INFO mapred.MapTask: bufstart = 7640048; bufend = 39737149; bufvoid = 99614720
12/10/28 00:58:24 INFO mapred.MapTask: kvstart = 196603; kvend = 131066; length = 327680
12/10/28 00:58:26 INFO mapred.MapTask: Finished spill 7
12/10/28 00:58:26 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:27 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:27 INFO mapred.MapTask: bufstart = 39737149; bufend = 69183305; bufvoid = 99614720
12/10/28 00:58:27 INFO mapred.MapTask: kvstart = 131066; kvend = 65529; length = 327680
12/10/28 00:58:27 INFO mapred.JobClient:  map 21% reduce 0%
12/10/28 00:58:28 INFO mapred.MapTask: Finished spill 8
12/10/28 00:58:29 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:29 INFO mapred.MapTask: bufstart = 69183305; bufend = 97875327; bufvoid = 99614720
12/10/28 00:58:29 INFO mapred.MapTask: kvstart = 65529; kvend = 327673; length = 327680
12/10/28 00:58:29 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:30 INFO mapred.JobClient:  map 26% reduce 0%
12/10/28 00:58:31 INFO mapred.MapTask: Finished spill 9
12/10/28 00:58:32 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:32 INFO mapred.MapTask: bufstart = 97875327; bufend = 31087133; bufvoid = 99614698
12/10/28 00:58:32 INFO mapred.MapTask: kvstart = 327673; kvend = 262136; length = 327680
12/10/28 00:58:32 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:33 INFO mapred.JobClient:  map 29% reduce 0%
12/10/28 00:58:33 INFO mapred.MapTask: Finished spill 10
12/10/28 00:58:34 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:34 INFO mapred.MapTask: bufstart = 31087133; bufend = 62067679; bufvoid = 99614720
12/10/28 00:58:34 INFO mapred.MapTask: kvstart = 262136; kvend = 196599; length = 327680
12/10/28 00:58:35 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:36 INFO mapred.MapTask: Finished spill 11
12/10/28 00:58:36 INFO mapred.JobClient:  map 31% reduce 0%
12/10/28 00:58:36 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:36 INFO mapred.MapTask: bufstart = 62067679; bufend = 96839215; bufvoid = 99614720
12/10/28 00:58:36 INFO mapred.MapTask: kvstart = 196599; kvend = 131062; length = 327680
12/10/28 00:58:38 INFO mapred.MapTask: Finished spill 12
12/10/28 00:58:38 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:39 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:39 INFO mapred.MapTask: bufstart = 96839215; bufend = 29204841; bufvoid = 99614697
12/10/28 00:58:39 INFO mapred.MapTask: kvstart = 131062; kvend = 65525; length = 327680
12/10/28 00:58:39 INFO mapred.JobClient:  map 36% reduce 0%
12/10/28 00:58:40 INFO mapred.MapTask: Finished spill 13
12/10/28 00:58:41 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:41 INFO mapred.MapTask: bufstart = 29204841; bufend = 59391566; bufvoid = 99614720
12/10/28 00:58:41 INFO mapred.MapTask: kvstart = 65525; kvend = 327669; length = 327680
12/10/28 00:58:41 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:42 INFO mapred.JobClient:  map 39% reduce 0%
12/10/28 00:58:42 INFO mapred.MapTask: Finished spill 14
12/10/28 00:58:43 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:43 INFO mapred.MapTask: bufstart = 59391566; bufend = 88629854; bufvoid = 99614720
12/10/28 00:58:43 INFO mapred.MapTask: kvstart = 327669; kvend = 262132; length = 327680
12/10/28 00:58:44 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:45 INFO mapred.MapTask: Finished spill 15
12/10/28 00:58:45 INFO mapred.JobClient:  map 42% reduce 0%
12/10/28 00:58:46 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:46 INFO mapred.MapTask: bufstart = 88629854; bufend = 19479345; bufvoid = 99614663
12/10/28 00:58:46 INFO mapred.MapTask: kvstart = 262132; kvend = 196595; length = 327680
12/10/28 00:58:47 INFO mapred.MapTask: Finished spill 16
12/10/28 00:58:47 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:48 INFO mapred.JobClient:  map 45% reduce 0%
12/10/28 00:58:48 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:48 INFO mapred.MapTask: bufstart = 19479345; bufend = 50425350; bufvoid = 99614720
12/10/28 00:58:48 INFO mapred.MapTask: kvstart = 196595; kvend = 131058; length = 327680
12/10/28 00:58:50 INFO mapred.MapTask: Finished spill 17
12/10/28 00:58:50 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:50 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:50 INFO mapred.MapTask: bufstart = 50425350; bufend = 81295514; bufvoid = 99614720
12/10/28 00:58:50 INFO mapred.MapTask: kvstart = 131058; kvend = 65521; length = 327680
12/10/28 00:58:51 INFO mapred.JobClient:  map 49% reduce 0%
12/10/28 00:58:52 INFO mapred.MapTask: Finished spill 18
12/10/28 00:58:53 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:53 INFO mapred.MapTask: bufstart = 81295514; bufend = 10297619; bufvoid = 99614693
12/10/28 00:58:53 INFO mapred.MapTask: kvstart = 65521; kvend = 327665; length = 327680
12/10/28 00:58:53 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:54 INFO mapred.JobClient:  map 53% reduce 0%
12/10/28 00:58:54 INFO mapred.MapTask: Finished spill 19
12/10/28 00:58:55 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:55 INFO mapred.MapTask: bufstart = 10297619; bufend = 40501081; bufvoid = 99614720
12/10/28 00:58:55 INFO mapred.MapTask: kvstart = 327665; kvend = 262128; length = 327680
12/10/28 00:58:56 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:58:57 INFO mapred.MapTask: Finished spill 20
12/10/28 00:58:57 INFO mapred.JobClient:  map 55% reduce 0%
12/10/28 00:58:57 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:58:57 INFO mapred.MapTask: bufstart = 40501081; bufend = 70713611; bufvoid = 99614720
12/10/28 00:58:57 INFO mapred.MapTask: kvstart = 262128; kvend = 196591; length = 327680
12/10/28 00:58:59 INFO mapred.MapTask: Finished spill 21
12/10/28 00:58:59 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:00 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:00 INFO mapred.MapTask: bufstart = 70713611; bufend = 3303900; bufvoid = 99614652
12/10/28 00:59:00 INFO mapred.MapTask: kvstart = 196591; kvend = 131054; length = 327680
12/10/28 00:59:00 INFO mapred.JobClient:  map 59% reduce 0%
12/10/28 00:59:02 INFO mapred.MapTask: Finished spill 22
12/10/28 00:59:02 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:02 INFO mapred.MapTask: bufstart = 3303900; bufend = 34088069; bufvoid = 99614720
12/10/28 00:59:02 INFO mapred.MapTask: kvstart = 131054; kvend = 65517; length = 327680
12/10/28 00:59:02 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:03 INFO mapred.JobClient:  map 63% reduce 0%
12/10/28 00:59:04 INFO mapred.MapTask: Finished spill 23
12/10/28 00:59:05 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:05 INFO mapred.MapTask: bufstart = 34088069; bufend = 63394277; bufvoid = 99614720
12/10/28 00:59:05 INFO mapred.MapTask: kvstart = 65517; kvend = 327661; length = 327680
12/10/28 00:59:05 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:06 INFO mapred.JobClient:  map 66% reduce 0%
12/10/28 00:59:06 INFO mapred.MapTask: Finished spill 24
12/10/28 00:59:07 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:07 INFO mapred.MapTask: bufstart = 63394277; bufend = 94566907; bufvoid = 99614720
12/10/28 00:59:07 INFO mapred.MapTask: kvstart = 327661; kvend = 262124; length = 327680
12/10/28 00:59:08 INFO mapred.MapTask: Finished spill 25
12/10/28 00:59:08 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:09 INFO mapred.JobClient:  map 70% reduce 0%
12/10/28 00:59:09 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:09 INFO mapred.MapTask: bufstart = 94566907; bufend = 29503862; bufvoid = 99614698
12/10/28 00:59:09 INFO mapred.MapTask: kvstart = 262124; kvend = 196587; length = 327680
12/10/28 00:59:11 INFO mapred.MapTask: Finished spill 26
12/10/28 00:59:12 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:12 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:12 INFO mapred.MapTask: bufstart = 29503862; bufend = 63726597; bufvoid = 99614720
12/10/28 00:59:12 INFO mapred.MapTask: kvstart = 196587; kvend = 131050; length = 327680
12/10/28 00:59:12 INFO mapred.JobClient:  map 73% reduce 0%
12/10/28 00:59:14 INFO mapred.MapTask: Finished spill 27
12/10/28 00:59:14 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:14 INFO mapred.MapTask: bufstart = 63726597; bufend = 99242470; bufvoid = 99614720
12/10/28 00:59:14 INFO mapred.MapTask: kvstart = 131050; kvend = 65513; length = 327680
12/10/28 00:59:15 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:15 INFO mapred.JobClient:  map 77% reduce 0%
12/10/28 00:59:16 INFO mapred.MapTask: Finished spill 28
12/10/28 00:59:17 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:17 INFO mapred.MapTask: bufstart = 99242470; bufend = 35558411; bufvoid = 99614660
12/10/28 00:59:17 INFO mapred.MapTask: kvstart = 65513; kvend = 327657; length = 327680
12/10/28 00:59:18 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:18 INFO mapred.JobClient:  map 80% reduce 0%
12/10/28 00:59:18 INFO mapred.MapTask: Finished spill 29
12/10/28 00:59:19 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:19 INFO mapred.MapTask: bufstart = 35558411; bufend = 70034163; bufvoid = 99614720
12/10/28 00:59:19 INFO mapred.MapTask: kvstart = 327657; kvend = 262120; length = 327680
12/10/28 00:59:21 INFO mapred.MapTask: Finished spill 30
12/10/28 00:59:21 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:21 INFO mapred.JobClient:  map 83% reduce 0%
12/10/28 00:59:21 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:21 INFO mapred.MapTask: bufstart = 70034163; bufend = 4759655; bufvoid = 99614713
12/10/28 00:59:21 INFO mapred.MapTask: kvstart = 262120; kvend = 196583; length = 327680
12/10/28 00:59:24 INFO mapred.MapTask: Finished spill 31
12/10/28 00:59:24 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:24 INFO mapred.JobClient:  map 85% reduce 0%
12/10/28 00:59:24 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:24 INFO mapred.MapTask: bufstart = 4759655; bufend = 39709563; bufvoid = 99614720
12/10/28 00:59:24 INFO mapred.MapTask: kvstart = 196583; kvend = 131046; length = 327680
12/10/28 00:59:26 INFO mapred.MapTask: Finished spill 32
12/10/28 00:59:27 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:27 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:27 INFO mapred.MapTask: bufstart = 39709563; bufend = 74269540; bufvoid = 99614720
12/10/28 00:59:27 INFO mapred.MapTask: kvstart = 131046; kvend = 65509; length = 327680
12/10/28 00:59:27 INFO mapred.JobClient:  map 89% reduce 0%
12/10/28 00:59:29 INFO mapred.MapTask: Finished spill 33
12/10/28 00:59:29 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:29 INFO mapred.MapTask: bufstart = 74269540; bufend = 9768351; bufvoid = 99614650
12/10/28 00:59:29 INFO mapred.MapTask: kvstart = 65509; kvend = 327653; length = 327680
12/10/28 00:59:30 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:30 INFO mapred.JobClient:  map 93% reduce 0%
12/10/28 00:59:31 INFO mapred.MapTask: Finished spill 34
12/10/28 00:59:32 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:32 INFO mapred.MapTask: bufstart = 9768351; bufend = 43640794; bufvoid = 99614720
12/10/28 00:59:32 INFO mapred.MapTask: kvstart = 327653; kvend = 262116; length = 327680
12/10/28 00:59:33 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:33 INFO mapred.JobClient:  map 96% reduce 0%
12/10/28 00:59:33 INFO mapred.MapTask: Finished spill 35
12/10/28 00:59:34 INFO mapred.MapTask: Spilling map output: record full = true
12/10/28 00:59:34 INFO mapred.MapTask: bufstart = 43640794; bufend = 77787072; bufvoid = 99614720
12/10/28 00:59:34 INFO mapred.MapTask: kvstart = 262116; kvend = 196579; length = 327680
12/10/28 00:59:36 INFO mapred.MapTask: Finished spill 36
12/10/28 00:59:36 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:36 INFO mapred.MapTask: Starting flush of map output
12/10/28 00:59:36 INFO mapred.JobClient:  map 99% reduce 0%
12/10/28 00:59:37 INFO mapred.MapTask: Finished spill 37
12/10/28 00:59:37 INFO mapred.Merger: Merging 38 sorted segments
12/10/28 00:59:37 INFO mapred.Merger: Merging 2 intermediate segments out of a total of 38
12/10/28 00:59:38 INFO mapred.Merger: Merging 10 intermediate segments out of a total of 37
12/10/28 00:59:39 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:39 INFO mapred.JobClient:  map 100% reduce 0%
12/10/28 00:59:42 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 00:59:45 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:21 INFO mapred.Merger: Merging 10 intermediate segments out of a total of 28
12/10/28 01:00:24 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:27 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:28 INFO mapred.Merger: Merging 10 intermediate segments out of a total of 19
12/10/28 01:00:30 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:33 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:35 INFO mapred.Merger: Down to the last merge-pass, with 10 segments left of total size: 512806627 bytes
12/10/28 01:00:36 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:39 INFO mapred.Task: Task:attempt_local_0001_m_000000_0 is done. And is in the process of commiting
12/10/28 01:00:39 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:39 INFO mapred.LocalJobRunner: hdfs://localhost:9000/user/hadoop/webData/data12.out:0+66123962
12/10/28 01:00:39 INFO mapred.Task: Task 'attempt_local_0001_m_000000_0' done.
12/10/28 01:00:39 INFO mapred.Task:  Using ResourceCalculatorPlugin : org.apache.hadoop.util.LinuxResourceCalculatorPlugin@61f533
12/10/28 01:00:39 INFO mapred.LocalJobRunner: 
12/10/28 01:00:39 INFO mapred.Merger: Merging 1 sorted segments
12/10/28 01:00:39 INFO mapred.Merger: Down to the last merge-pass, with 0 segments left of total size: 0 bytes
12/10/28 01:00:39 INFO mapred.LocalJobRunner: 
12/10/28 01:00:39 INFO mapred.Task: Task:attempt_local_0001_r_000000_0 is done. And is in the process of commiting
12/10/28 01:00:39 INFO mapred.LocalJobRunner: 
12/10/28 01:00:39 INFO mapred.Task: Task attempt_local_0001_r_000000_0 is allowed to commit now
12/10/28 01:00:39 INFO mapred.FileOutputCommitter: Saved output of task 'attempt_local_0001_r_000000_0' to hdfs://localhost:9000/user/hadoop/webDataOut
12/10/28 01:00:42 INFO mapred.LocalJobRunner: reduce > reduce
12/10/28 01:00:42 INFO mapred.Task: Task 'attempt_local_0001_r_000000_0' done.
12/10/28 01:00:42 INFO mapred.JobClient:  map 100% reduce 100%
12/10/28 01:00:42 INFO mapred.JobClient: Job complete: job_local_0001
12/10/28 01:00:42 INFO mapred.JobClient: Counters: 22
12/10/28 01:00:42 INFO mapred.JobClient:   File Input Format Counters 
12/10/28 01:00:42 INFO mapred.JobClient:     Bytes Read=66123962
12/10/28 01:00:42 INFO mapred.JobClient:   File Output Format Counters 
12/10/28 01:00:42 INFO mapred.JobClient:     Bytes Written=0
12/10/28 01:00:42 INFO mapred.JobClient:   FileSystemCounters
12/10/28 01:00:42 INFO mapred.JobClient:     FILE_BYTES_READ=1866062016
12/10/28 01:00:42 INFO mapred.JobClient:     HDFS_BYTES_READ=132247924
12/10/28 01:00:42 INFO mapred.JobClient:     FILE_BYTES_WRITTEN=1866142216
12/10/28 01:00:42 INFO mapred.JobClient:   Map-Reduce Framework
12/10/28 01:00:42 INFO mapred.JobClient:     Map output materialized bytes=6
12/10/28 01:00:42 INFO mapred.JobClient:     Map input records=19405
12/10/28 01:00:42 INFO mapred.JobClient:     Reduce shuffle bytes=0
12/10/28 01:00:42 INFO mapred.JobClient:     Spilled Records=7484422
12/10/28 01:00:42 INFO mapred.JobClient:     Map output bytes=1192717378
12/10/28 01:00:42 INFO mapred.JobClient:     Total committed heap usage (bytes)=845938688
12/10/28 01:00:42 INFO mapred.JobClient:     CPU time spent (ms)=0
12/10/28 01:00:42 INFO mapred.JobClient:     Map input bytes=66123962
12/10/28 01:00:42 INFO mapred.JobClient:     SPLIT_RAW_BYTES=105
12/10/28 01:00:42 INFO mapred.JobClient:     Combine input records=13954115
12/10/28 01:00:42 INFO mapred.JobClient:     Reduce input records=0
12/10/28 01:00:42 INFO mapred.JobClient:     Reduce input groups=0
12/10/28 01:00:42 INFO mapred.JobClient:     Combine output records=4111513
12/10/28 01:00:42 INFO mapred.JobClient:     Physical memory (bytes) snapshot=0
12/10/28 01:00:42 INFO mapred.JobClient:     Reduce output records=0
12/10/28 01:00:42 INFO mapred.JobClient:     Virtual memory (bytes) snapshot=0
12/10/28 01:00:42 INFO mapred.JobClient:     Map output records=9842602
SEInvertedIndex Program ends!...

我的实现非常简单，当输入文件很小时它工作得很好。多谢！

这是代码:

package com.zhoutall.SEInvertedIndex;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.util.Iterator;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.SequenceFileInputFormat;
import org.apache.hadoop.mapred.SequenceFileOutputFormat;
import org.wltea.analyzer.core.IKSegmenter;
import org.wltea.analyzer.core.Lexeme;

public class SEInvertedIndex {


    public static class InvertedIndexMapper extends MapReduceBase implements
            Mapper<LongWritable, Text, Text, Text> {
        private final static Text One = new Text("1");

        public void map(LongWritable key, Text val,
                OutputCollector<Text, Text> output, Reporter reporter)
                throws IOException {

            String strContent_all=new String(val.getBytes(), 0, val.getLength(), "utf-8");
            if(strContent_all==null || strContent_all=="\n")
                return;
//          System.out.println(strContent_all);
            String strUrl=null;
            String strContent = null;
            String strPart[] = strContent_all.split("   ");
//          if(strPart.length!=2)
//              return;
            strUrl = strPart[0].replace("http", "https");
            strContent = strPart[1];
            //System.out.println(strUrl+"~~"+strContent);

            String webHead = new String(strContent.substring(0, 20) + "...").replace("&nbsp;", " ");
            StringReader strReader = new StringReader(strContent);
            IKSegmenter ik = new IKSegmenter(strReader, true);
            Lexeme lexeme = null;
            while ((lexeme = ik.next()) != null) {
                // System.out.println(lexeme.getLexemeText() + "##" + strUrl + "##" + webHead);
                output.collect(new Text(lexeme.getLexemeText() + "##" + strUrl + "##" + webHead), One);
            }
        }
    }

    public static class InvertedIndexCombiner extends MapReduceBase implements
            Reducer<Text, Text, Text, Text> {

        public void reduce(Text key, Iterator<Text> values,
                OutputCollector<Text, Text> output, Reporter reporter)
                throws IOException {
            int sum = 0;
            while (values.hasNext()) {
                values.next();
                sum += 1;
            }
//          System.out.println(key.toString());
            String fields[] = key.toString().split("##");
            if(fields.length!=3)
                return;
//          System.out.println(fields[1]+"##"+fields[2] + "##" + sum);
            output.collect(new Text(fields[0]), new Text(fields[1] + "##" + fields[2] + "##" + sum));
        }
    }

    public static class InvertedIndexReducer extends MapReduceBase implements
            Reducer<Text, Text, Text, Text> {

        public void reduce(Text key, Iterator<Text> values,
                OutputCollector<Text, Text> output, Reporter reporter)
                throws IOException {

            boolean first = true;
            StringBuilder count_all = new StringBuilder();

            while (values.hasNext()) {
                if (!first)
                    count_all.append(";;");
                first = false;
                count_all.append(values.next().toString());
            }
//          System.out.println(key+"::"+count_all.toString());
            output.collect(key, new Text(count_all.toString()));
        }
    }

    public static void main(String[] args) {
        System.out.println("SEInvertedIndex Program starts!...");
        JobClient client = new JobClient();
        JobConf conf = new JobConf(SEInvertedIndex.class);

        conf.setJobName("SEInvertedIndex");

        conf.setOutputKeyClass(Text.class);
        conf.setOutputValueClass(Text.class);
        //conf.setNumReduceTasks(1);
        FileInputFormat.addInputPath(conf, new Path(args[0]));
        FileOutputFormat.setOutputPath(conf, new Path(args[1]));
        // ////////////////
        Path dstFilePath = new Path(args[1]);
        FileSystem fs = null;
        try {
            fs = dstFilePath.getFileSystem(conf);
            if (fs.exists(dstFilePath))
                fs.delete(dstFilePath, true);
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        // /////////////////
        conf.setMapperClass(InvertedIndexMapper.class);
        conf.setCombinerClass(InvertedIndexCombiner.class);
        conf.setReducerClass(InvertedIndexReducer.class);

        client.setConf(conf);

        try {
            JobClient.runJob(conf);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("SEInvertedIndex Program ends!...");
    }
}

Answer 1

您的组合器实现存在问题。

从柜台你可以看到有问题：

Combine input records=13954115
Reduce input records=0
Reduce input groups=0
Combine output records=4111513

此细分不会显示您，但组合器同时运行 map 端和 reduce 端 - 作业跟踪器 Web UI 页面应该为您提供完整的细分。

无论如何，组合器映射端会改变键，如果它再次通过组合器（映射或减少端）被字段长度拒绝！= 3条件：

if(fields.length!=3)
    return;
output.collect(new Text(fields[0]), new Text(fields[1] + "##" + fields[2] + "##" + sum));

因此，在这里您要修改输入键并将字段 [0] 作为键输出（并且该值看起来像您应该作为键输出的值 - 它有 3 个字段 ## 分隔），现在如果此数据通过再次组合器映射端（这是可能的），它将被拒绝。从 map 端组合器输出的任何数据都将被 reduce 端拒绝，因为键现在确实包含 3 个## 分隔字段。

与您的问题无关，您可能还想查看代码的其他部分（例如在映射器中）：

String strContent_all=new String(val.getBytes(), 0, val.getLength(), "utf-8");
if(strContent_all==null || strContent_all=="\n")
    return;

这个条件永远不会触发 true 因为 strContent 永远不会为空，你应该using strContent_all.equals("\n")而不是==测试引用相等性。

Answer 2

日志显示写入了大量的 map 记录，但读入了 0（零）个 reduce 记录。

如果我不得不猜测，记录会在您用于拆分组合器中的记录的正则表达式“##”中丢失。“#”在正则表达式中用作注释，因此您可能不会像您认为的那样拆分记录。您的逻辑表明，如果您不拆分为 3 个子字符串，则不会写出任何内容。

尝试使用：

String fields[] = key.toString().split("\\#\\#");

这逃脱了“#”的。

顺便提一句。我尝试将逻辑从 map() 和 reduce() 方法中分解出来，这样我就可以通过 JUnit 测试来实现它。我还尝试使用计数器来指示我何时何地退出这些方法。这些做法非常好，如果我自己这么说的话，它们将有助于解决这样的问题（即使我完全错误地认为代码无法正常工作：）