spark下統計單詞頻次

寫了一個簡單的語句，還沒有優化：

scala> sc.
     | textFile("/etc/profile").
     | flatMap((s:String)=>s.split("\\s")).
     | map(_.toUpperCase).
     | map((s:String)=>(s, 1)).
     | filter((pair)=>pair._1.forall((ch)=>ch>'A'&&ch<'Z')).
     | reduceByKey(_+_).
     | sortByKey().
     | foreach(println)

注意這程式碼還可以優化：

scala> sc.
     | textFile("/etc/profile").
     | flatMap(_.split("\\s")).
     | map(_.toUpperCase).
     | map((_, 1)).
     | filter(_._1.forall((ch)=>ch>'A'&&ch<'Z')).
     | reduceByKey(_+_).
     | sortByKey().
     | foreach(println)

輸出結果如下：

15/03/06 08:50:44 INFO MemoryStore: ensureFreeSpace(75904) called with curMem=259812, maxMem=277842493
15/03/06 08:50:44 INFO MemoryStore: Block broadcast_10 stored as values in memory (estimated size 74.1 KB, free 264.7 MB)
15/03/06 08:50:44 INFO FileInputFormat: Total input paths to process : 1
15/03/06 08:50:44 INFO SparkContext: Starting job: sortByKey at <console>:20
15/03/06 08:50:44 INFO DAGScheduler: Registering RDD 25 (filter at <console>:18)
15/03/06 08:50:44 INFO DAGScheduler: Got job 4 (sortByKey at <console>:20) with 2 output partitions (allowLocal=false)
15/03/06 08:50:44 INFO DAGScheduler: Final stage: Stage 10(sortByKey at <console>:20)
15/03/06 08:50:44 INFO DAGScheduler: Parents of final stage: List(Stage 11)
15/03/06 08:50:44 INFO DAGScheduler: Missing parents: List(Stage 11)
15/03/06 08:50:44 INFO DAGScheduler: Submitting Stage 11 (FilteredRDD[25] at filter at <console>:18), which has no missing parents
15/03/06 08:50:44 INFO MemoryStore: ensureFreeSpace(3736) called with curMem=335716, maxMem=277842493
15/03/06 08:50:44 INFO MemoryStore: Block broadcast_11 stored as values in memory (estimated size 3.6 KB, free 264.6 MB)
15/03/06 08:50:44 INFO DAGScheduler: Submitting 2 missing tasks from Stage 11 (FilteredRDD[25] at filter at <console>:18)
15/03/06 08:50:44 INFO TaskSchedulerImpl: Adding task set 11.0 with 2 tasks
15/03/06 08:50:44 INFO TaskSetManager: Starting task 0.0 in stage 11.0 (TID 16, localhost, PROCESS_LOCAL, 1162 bytes)
15/03/06 08:50:44 INFO TaskSetManager: Starting task 1.0 in stage 11.0 (TID 17, localhost, PROCESS_LOCAL, 1162 bytes)
15/03/06 08:50:44 INFO Executor: Running task 1.0 in stage 11.0 (TID 17)
15/03/06 08:50:44 INFO Executor: Running task 0.0 in stage 11.0 (TID 16)
15/03/06 08:50:44 INFO HadoopRDD: Input split: file:/etc/profile:1189+1189
15/03/06 08:50:44 INFO HadoopRDD: Input split: file:/etc/profile:0+1189
15/03/06 08:50:44 INFO Executor: Finished task 1.0 in stage 11.0 (TID 17). 1863 bytes result sent to driver
15/03/06 08:50:44 INFO TaskSetManager: Finished task 1.0 in stage 11.0 (TID 17) in 43 ms on localhost (1/2)
15/03/06 08:50:44 INFO Executor: Finished task 0.0 in stage 11.0 (TID 16). 1863 bytes result sent to driver
15/03/06 08:50:44 INFO TaskSetManager: Finished task 0.0 in stage 11.0 (TID 16) in 51 ms on localhost (2/2)
15/03/06 08:50:44 INFO DAGScheduler: Stage 11 (filter at <console>:18) finished in 0.054 s
15/03/06 08:50:44 INFO DAGScheduler: looking for newly runnable stages
15/03/06 08:50:44 INFO DAGScheduler: running: Set()
15/03/06 08:50:44 INFO DAGScheduler: waiting: Set(Stage 10)
15/03/06 08:50:44 INFO DAGScheduler: failed: Set()
15/03/06 08:50:44 INFO TaskSchedulerImpl: Removed TaskSet 11.0, whose tasks have all completed, from pool 
15/03/06 08:50:44 INFO DAGScheduler: Missing parents for Stage 10: List()
15/03/06 08:50:44 INFO DAGScheduler: Submitting Stage 10 (MapPartitionsRDD[28] at sortByKey at <console>:20), which is now runnable
15/03/06 08:50:44 INFO MemoryStore: ensureFreeSpace(2856) called with curMem=339452, maxMem=277842493
15/03/06 08:50:44 INFO MemoryStore: Block broadcast_12 stored as values in memory (estimated size 2.8 KB, free 264.6 MB)
15/03/06 08:50:44 INFO DAGScheduler: Submitting 2 missing tasks from Stage 10 (MapPartitionsRDD[28] at sortByKey at <console>:20)
15/03/06 08:50:44 INFO TaskSchedulerImpl: Adding task set 10.0 with 2 tasks
15/03/06 08:50:44 INFO TaskSetManager: Starting task 0.0 in stage 10.0 (TID 18, localhost, PROCESS_LOCAL, 948 bytes)
15/03/06 08:50:44 INFO TaskSetManager: Starting task 1.0 in stage 10.0 (TID 19, localhost, PROCESS_LOCAL, 948 bytes)
15/03/06 08:50:44 INFO Executor: Running task 0.0 in stage 10.0 (TID 18)
15/03/06 08:50:44 INFO Executor: Running task 1.0 in stage 10.0 (TID 19)
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: maxBytesInFlight: 50331648, targetRequestSize: 10066329
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Started 0 remote fetches in 0 ms
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: maxBytesInFlight: 50331648, targetRequestSize: 10066329
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Started 0 remote fetches in 0 ms
15/03/06 08:50:44 INFO Executor: Finished task 0.0 in stage 10.0 (TID 18). 1165 bytes result sent to driver
15/03/06 08:50:44 INFO TaskSetManager: Finished task 0.0 in stage 10.0 (TID 18) in 18 ms on localhost (1/2)
15/03/06 08:50:44 INFO Executor: Finished task 1.0 in stage 10.0 (TID 19). 1293 bytes result sent to driver
15/03/06 08:50:44 INFO TaskSetManager: Finished task 1.0 in stage 10.0 (TID 19) in 28 ms on localhost (2/2)
15/03/06 08:50:44 INFO DAGScheduler: Stage 10 (sortByKey at <console>:20) finished in 0.031 s
15/03/06 08:50:44 INFO TaskSchedulerImpl: Removed TaskSet 10.0, whose tasks have all completed, from pool 
15/03/06 08:50:44 INFO SparkContext: Job finished: sortByKey at <console>:20, took 0.107864348 s
15/03/06 08:50:44 INFO SparkContext: Starting job: foreach at <console>:21
15/03/06 08:50:44 INFO MapOutputTrackerMaster: Size of output statuses for shuffle 4 is 144 bytes
15/03/06 08:50:44 INFO DAGScheduler: Registering RDD 26 (reduceByKey at <console>:19)
15/03/06 08:50:44 INFO DAGScheduler: Got job 5 (foreach at <console>:21) with 2 output partitions (allowLocal=false)
15/03/06 08:50:44 INFO DAGScheduler: Final stage: Stage 12(foreach at <console>:21)
15/03/06 08:50:44 INFO DAGScheduler: Parents of final stage: List(Stage 14)
15/03/06 08:50:44 INFO DAGScheduler: Missing parents: List(Stage 14)
15/03/06 08:50:44 INFO DAGScheduler: Submitting Stage 14 (ShuffledRDD[26] at reduceByKey at <console>:19), which has no missing parents
15/03/06 08:50:44 INFO MemoryStore: ensureFreeSpace(2472) called with curMem=342308, maxMem=277842493
15/03/06 08:50:44 INFO MemoryStore: Block broadcast_13 stored as values in memory (estimated size 2.4 KB, free 264.6 MB)
15/03/06 08:50:44 INFO DAGScheduler: Submitting 2 missing tasks from Stage 14 (ShuffledRDD[26] at reduceByKey at <console>:19)
15/03/06 08:50:44 INFO TaskSchedulerImpl: Adding task set 14.0 with 2 tasks
15/03/06 08:50:44 INFO TaskSetManager: Starting task 0.0 in stage 14.0 (TID 20, localhost, PROCESS_LOCAL, 937 bytes)
15/03/06 08:50:44 INFO TaskSetManager: Starting task 1.0 in stage 14.0 (TID 21, localhost, PROCESS_LOCAL, 937 bytes)
15/03/06 08:50:44 INFO Executor: Running task 1.0 in stage 14.0 (TID 21)
15/03/06 08:50:44 INFO Executor: Running task 0.0 in stage 14.0 (TID 20)
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: maxBytesInFlight: 50331648, targetRequestSize: 10066329
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Started 0 remote fetches in 0 ms
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: maxBytesInFlight: 50331648, targetRequestSize: 10066329
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
15/03/06 08:50:44 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Started 0 remote fetches in 1 ms
15/03/06 08:50:44 INFO Executor: Finished task 1.0 in stage 14.0 (TID 21). 996 bytes result sent to driver
15/03/06 08:50:44 INFO TaskSetManager: Finished task 1.0 in stage 14.0 (TID 21) in 14 ms on localhost (1/2)
15/03/06 08:50:44 INFO Executor: Finished task 0.0 in stage 14.0 (TID 20). 996 bytes result sent to driver
15/03/06 08:50:44 INFO TaskSetManager: Finished task 0.0 in stage 14.0 (TID 20) in 21 ms on localhost (2/2)
15/03/06 08:50:44 INFO TaskSchedulerImpl: Removed TaskSet 14.0, whose tasks have all completed, from pool 
15/03/06 08:50:44 INFO DAGScheduler: Stage 14 (reduceByKey at <console>:19) finished in 0.022 s
15/03/06 08:50:44 INFO DAGScheduler: looking for newly runnable stages
15/03/06 08:50:44 INFO DAGScheduler: running: Set()
15/03/06 08:50:44 INFO DAGScheduler: waiting: Set(Stage 12)
15/03/06 08:50:44 INFO DAGScheduler: failed: Set()
15/03/06 08:50:44 INFO DAGScheduler: Missing parents for Stage 12: List()
15/03/06 08:50:44 INFO DAGScheduler: Submitting Stage 12 (ShuffledRDD[29] at sortByKey at <console>:20), which is now runnable
15/03/06 08:50:44 INFO MemoryStore: ensureFreeSpace(2304) called with curMem=344780, maxMem=277842493
15/03/06 08:50:44 INFO MemoryStore: Block broadcast_14 stored as values in memory (estimated size 2.3 KB, free 264.6 MB)
15/03/06 08:50:44 INFO DAGScheduler: Submitting 2 missing tasks from Stage 12 (ShuffledRDD[29] at sortByKey at <console>:20)
15/03/06 08:50:44 INFO TaskSchedulerImpl: Adding task set 12.0 with 2 tasks
15/03/06 08:50:44 INFO TaskSetManager: Starting task 0.0 in stage 12.0 (TID 22, localhost, PROCESS_LOCAL, 948 bytes)
15/03/06 08:50:44 INFO TaskSetManager: Starting task 1.0 in stage 12.0 (TID 23, localhost, PROCESS_LOCAL, 948 bytes)
15/03/06 08:50:45 INFO Executor: Running task 1.0 in stage 12.0 (TID 23)
15/03/06 08:50:45 INFO Executor: Running task 0.0 in stage 12.0 (TID 22)
15/03/06 08:50:45 INFO BlockFetcherIterator$BasicBlockFetcherIterator: maxBytesInFlight: 50331648, targetRequestSize: 10066329
15/03/06 08:50:45 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
15/03/06 08:50:45 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Started 0 remote fetches in 0 ms
15/03/06 08:50:45 INFO BlockFetcherIterator$BasicBlockFetcherIterator: maxBytesInFlight: 50331648, targetRequestSize: 10066329
15/03/06 08:50:45 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
15/03/06 08:50:45 INFO BlockFetcherIterator$BasicBlockFetcherIterator: Started 0 remote fetches in 0 ms
(LOGIN,2)
(MERGING,1)
(MUCH,1)
(NEED,1)
(NOT,1)
(PREVENT,1)
(RESERVED,1)
(SCRIPT,1)
(SETS,1)
(SETUP,1)
(SHELL,2)
(SYSTEM,2)
(THE,1)
(THEN,8)
(THIS,3)
(THRESHOLD,1)
(TO,5)
(UIDGID,1)
(UNLESS,1)
(UNSET,2)
(USER,1)
(WE,1)
(WIDE,1)
(WILL,1)
(YOU,3)
(YOUR,1)
15/03/06 08:50:45 INFO Executor: Finished task 1.0 in stage 12.0 (TID 23). 826 bytes result sent to driver
15/03/06 08:50:45 INFO TaskSetManager: Finished task 1.0 in stage 12.0 (TID 23) in 13 ms on localhost (1/2)
(,260)
(BETTER,1)
(BY,1)
(CHECK,1)
(COULD,1)
(CURRENT,1)
(CUSTOM,1)
(DO,1)
(DONE,1)
(ELSE,5)
(ENVIRONMENT,1)
(EXPORT,15)
(FI,8)
(FILE,2)
(FOR,5)
(FUNCTIONS,1)
(FUTURE,1)
(GET,1)
(GO,1)
(GOOD,1)
(HISTCONTROL,1)
(I,2)
(IF,8)
(IN,6)
(IS,1)
(IT,1)
(KNOW,1)
(KSH,1)
15/03/06 08:50:45 INFO Executor: Finished task 0.0 in stage 12.0 (TID 22). 826 bytes result sent to driver
15/03/06 08:50:45 INFO TaskSetManager: Finished task 0.0 in stage 12.0 (TID 22) in 27 ms on localhost (2/2)
15/03/06 08:50:45 INFO TaskSchedulerImpl: Removed TaskSet 12.0, whose tasks have all completed, from pool 
15/03/06 08:50:45 INFO DAGScheduler: Stage 12 (foreach at <console>:21) finished in 0.025 s
15/03/06 08:50:45 INFO SparkContext: Job finished: foreach at <console>:21, took 0.07397057 s

---

通過如下程式碼，可以輸出參與計算的節點名稱，注意start-all並指定shell的–master引數：

spark-shell --master spark://bluejoe0:7077

程式碼如下：

rdd.mapPartitions(_=>Array[String](("hostname" !!).trim).iterator, false).collect

res28: Array[String] = Array(bluejoe4, bluejoe5)