Map Reduce执行流程以及Hive执行insert overwrite 底层是怎么跑数据的_hive中overwrite 执行顺序‘’

目录

MR简述

MR执行流程

Input阶段

Mapper阶段

Reducer阶段

例子

insert overwrite table

翻译日志

MR简述

MapReduce 作业通常将输入数据集分割成独立的块，这些块由 map 任务以完全并行的方式进行处理。MR框架对映射的输出进行排序，然后将其输入到 reduce 任务中。通常，作业的输入和输出都存储在文件系统中。该框架负责调度任务、监视任务并重新执行失败的任务。

通常，计算节点和存储节点是相同的，也就是说，MapReduce 框架和 Hadoop 分布式文件系统在同一组节点上运行。这种配置允许框架在数据已经存在的节点上有效地调度任务，从而产生跨集群的高聚合带宽。

MR执行流程

Input阶段

• JobClient 输入输入文件的存储位置
• JobClient 通过 InputFormat 接口指定分割的逻辑，默认是按照 HDFS 文件分隔，即有多少个数据块就有多少个 maps
• Hadoop 再次把文件分割为 <key, value> 类型的数据
• JobTracker 负责分配对应的数据块由对应的 mapper 处理，同时 RecordReader 负责读取 KV 值

Mapper阶段

• Jobtracker 会将 maptask 分发给 TaskTracker 去执行
• mapper 接收到数据之后，会在 Hadoop 的内存缓冲区（默认大小100M）中按照 key 进行排序分区操作，待内存写满之后，会写入磁盘
• 将不同 key 的数据进行 partition 操作，即相同 key 的数据在同一个分区当中
• 在单个分区内按照 key 进行排序 sort 操作
• Combiner 阶段（可选），从所有 map 主机上把相同的 key 的 key value 对组合在一起，减小 reduce 的压力
• map 将数据写出到文件系统

Reducer阶段

Reducer 有三个主要阶段：grouping，sortpartiton，reduce

• Shuffle：reduce 通过 HTTP 获取所有 mapper 输出的分区数据
• Grouping：Reduce 将不同 map 端的相同 key 的数据进行分组，因为不同的 mapper 可能输入相同 key 的数据
• Sort：在 reduce 阶段进行，对 mapper 的数据会进行排序的操作，这个过程称为 sort

注意：Shuffle 和 Sort 同时进行，当获取 map 输出时，它们被合并。

• Secondary Sort：如果使用  Job.setSortComparatorClass(Class)，那么就会对数据进行自定义排序。由于  Job.setGroupingComparatorClass(Class) 可用于控制中间键的分组方式，因此可以将这些键与值结合使用来模拟二次排序
• Reduce：使用 reduce(WritableComparable, Iterable<Writable>, Context) 方法遍历 <key, (list of values)> 类型的数据，最后将数据写入文件系统

Reduce 的数量可以由 Job.setNumReduceTasks(int) 指定。//数量必须比 partition 分区的数量大，不然会报错

例子

hive 任务的底层就是 MapReduce 任务

insert overwrite table

0: jdbc:hive2://hiveserver2.bigdata.chinatele> insert OVERWRITE table jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d PARTITION (data_day)
. . . . . . . . . . . . . . . . . . . . . . .> select * from sc_share_db.app_mbl_user_trmnl_trail_info_d a where a.data_day BETWEEN 20190619 AND 20191007;
INFO  : Compiling command(queryId=hive_20191010113232_c82e18e3-5853-43c5-9856-d1d1c55dde45): insert OVERWRITE table jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d PARTITION (data_day)
select * from sc_share_db.app_mbl_user_trmnl_trail_info_d a where a.data_day BETWEEN 20190619 AND 20191007
INFO  : Semantic Analysis Completed
INFO  : Returning Hive schema: Schema(fieldSchemas:[FieldSchema(name:a.mdn, type:string, comment:null), FieldSchema(name:a.r_trmnl_brand, type:string, comment:null), FieldSchema(name:a.r_trmnl_model, type:string, comment:null), FieldSchema(name:a.r_use_day, type:string, comment:null), FieldSchema(name:a.d_trmnl_brand, type:string, comment:null), FieldSchema(name:a.d_trmnl_model, type:string, comment:null), FieldSchema(name:a.d_use_day, type:string, comment:null), FieldSchema(name:a.data_day, type:string, comment:null)], properties:null)
INFO  : Completed compiling command(queryId=hive_20191010113232_c82e18e3-5853-43c5-9856-d1d1c55dde45); Time taken: 0.412 seconds
INFO  : Concurrency mode is disabled, not creating a lock manager
INFO  : Executing command(queryId=hive_20191010113232_c82e18e3-5853-43c5-9856-d1d1c55dde45): insert OVERWRITE table jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d PARTITION (data_day)
select * from sc_share_db.app_mbl_user_trmnl_trail_info_d a where a.data_day BETWEEN 20190619 AND 20191007
INFO  : Query ID = hive_20191010113232_c82e18e3-5853-43c5-9856-d1d1c55dde45
INFO  : Total jobs = 3
INFO  : Launching Job 1 out of 3
INFO  : Starting task [Stage-1:MAPRED] in serial mode
INFO  : Number of reduce tasks is set to 0 since there's no reduce operator
INFO  : number of splits:237
INFO  : Submitting tokens for job: job_1569295562481_2677748
INFO  : Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:ns4, Ident: (token for jt_jtsjzxsjyyc_sc_fwfz: HDFS_DELEGATION_TOKEN owner=jt_jtsjzxsjyyc_sc_fwfz, renewer=yarn, realUser=hive/hiveserver2.bigdata.chinatelecom.cn@HADOOP.CHINATELECOM.CN, issueDate=1570678407251, maxDate=1571283207251, sequenceNumber=99889585, masterKeyId=889)
INFO  : Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:ns3, Ident: (token for jt_jtsjzxsjyyc_sc_fwfz: HDFS_DELEGATION_TOKEN owner=jt_jtsjzxsjyyc_sc_fwfz, renewer=yarn, realUser=hive/hiveserver2.bigdata.chinatelecom.cn@HADOOP.CHINATELECOM.CN, issueDate=1570678407264, maxDate=1571283207264, sequenceNumber=100362646, masterKeyId=873)
INFO  : Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:ns, Ident: (token for jt_jtsjzxsjyyc_sc_fwfz: HDFS_DELEGATION_TOKEN owner=jt_jtsjzxsjyyc_sc_fwfz, renewer=yarn, realUser=hive/hiveserver2.bigdata.chinatelecom.cn@HADOOP.CHINATELECOM.CN, issueDate=1570678406757, maxDate=1571283206757, sequenceNumber=381027444, masterKeyId=1165)
INFO  : Kind: HIVE_DELEGATION_TOKEN, Service: HiveServer2ImpersonationToken, Ident: 00 16 6a 74 5f 6a 74 73 6a 7a 78 73 6a 79 79 63 5f 73 63 5f 66 77 66 7a 16 6a 74 5f 6a 74 73 6a 7a 78 73 6a 79 79 63 5f 73 63 5f 66 77 66 7a 3f 68 69 76 65 2f 68 69 76 65 73 65 72 76 65 72 32 2e 62 69 67 64 61 74 61 2e 63 68 69 6e 61 74 65 6c 65 63 6f 6d 2e 63 6e 40 48 41 44 4f 4f 50 2e 43 48 49 4e 41 54 45 4c 45 43 4f 4d 2e 43 4e 8a 01 6d b3 a7 a2 5e 8a 01 6d d7 b4 26 5e 8e 77 aa 8e 19 30
INFO  : Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:ns2, Ident: (token for jt_jtsjzxsjyyc_sc_fwfz: HDFS_DELEGATION_TOKEN owner=jt_jtsjzxsjyyc_sc_fwfz, renewer=yarn, realUser=hive/hiveserver2.bigdata.chinatelecom.cn@HADOOP.CHINATELECOM.CN, issueDate=1570678407250, maxDate=1571283207250, sequenceNumber=110691977, masterKeyId=871)
INFO  : The url to track the job: http://NM-304-RH5885V3-BIGDATA-008:8088/proxy/application_1569295562481_2677748/
INFO  : Starting Job = job_1569295562481_2677748, Tracking URL = http://NM-304-RH5885V3-BIGDATA-008:8088/proxy/application_1569295562481_2677748/
INFO  : Kill Command = /usr/lib/hadoop/bin/hadoop job  -kill job_1569295562481_2677748
INFO  : Hadoop job information for Stage-1: number of mappers: 237; number of reducers: 0
INFO  : 2019-10-10 11:35:34,427 Stage-1 map = 0%,  reduce = 0%
INFO  : 2019-10-10 11:36:18,032 Stage-1 map = 1%,  reduce = 0%, Cumulative CPU 10.65 sec
INFO  : 2019-10-10 11:36:19,080 Stage-1 map = 8%,  reduce = 0%, Cumulative CPU 96.18 sec
INFO  : 2019-10-10 11:36:20,131 Stage-1 map = 17%,  reduce = 0%, Cumulative CPU 224.8 sec
INFO  : 2019-10-10 11:36:21,181 Stage-1 map = 23%,  reduce = 0%, Cumulative CPU 342.52 sec
INFO  : 2019-10-10 11:36:22,243 Stage-1 map = 29%,  reduce = 0%, Cumulative CPU 444.37 sec
INFO  : 2019-10-10 11:36:23,304 Stage-1 map = 47%,  reduce = 0%, Cumulative CPU 1014.68 sec
INFO  : 2019-10-10 11:36:24,582 Stage-1 map = 64%,  reduce = 0%, Cumulative CPU 1638.8 sec
================================中间有一部分略
INFO  : 2019-10-10 11:36:37,280 Stage-1 map = 84%,  reduce = 0%, Cumulative CPU 2181.11 sec
INFO  : 2019-10-10 11:36:48,674 Stage-1 map = 86%,  reduce = 0%, Cumulative CPU 2209.67 sec
INFO  : 2019-10-10 11:37:01,292 Stage-1 map = 90%,  reduce = 0%, Cumulative CPU 2299.86 sec
INFO  : 2019-10-10 11:37:07,494 Stage-1 map = 92%,  reduce = 0%, Cumulative CPU 2322.2 sec
INFO  : 2019-10-10 11:37:12,849 Stage-1 map = 93%,  reduce = 0%, Cumulative CPU 2335.47 sec
INFO  : 2019-10-10 11:37:13,886 Stage-1 map = 97%,  reduce = 0%, Cumulative CPU 2363.0 sec
INFO  : 2019-10-10 11:37:14,922 Stage-1 map = 98%,  reduce = 0%, Cumulative CPU 2372.74 sec
INFO  : 2019-10-10 11:39:16,852 Stage-1 map = 99%,  reduce = 0%, Cumulative CPU 2386.92 sec
INFO  : 2019-10-10 11:46:52,457 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 2398.68 sec
INFO  : MapReduce Total cumulative CPU time: 39 minutes 58 seconds 680 msec
INFO  : Ended Job = job_1569295562481_2677748
INFO  : Starting task [Stage-7:CONDITIONAL] in serial mode
INFO  : Stage-4 is selected by condition resolver.
INFO  : Stage-3 is filtered out by condition resolver.
INFO  : Stage-5 is filtered out by condition resolver.
INFO  : Starting task [Stage-4:MOVE] in serial mode
INFO  : Moving data to: viewfs://ctccfs/user/hive_tmp/.hive-staging_hive_2019-10-10_11-32-41_413_3936369249909689263-4162/-ext-10000 from viewfs://ctccfs/user/hive_tmp/.hive-staging_hive_2019-10-10_11-32-41_413_3936369249909689263-4162/-ext-10002
INFO  : Starting task [Stage-0:MOVE] in serial mode
INFO  : Loading data to table jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d partition (data_day=null) from viewfs://ctccfs/user/hive_tmp/.hive-staging_hive_2019-10-10_11-32-41_413_3936369249909689263-4162/-ext-10000
INFO  :          Time taken for load dynamic partitions : 37085
INFO  :         Loading partition {data_day=20190915}
INFO  :         Loading partition {data_day=20190624}
INFO  :         Loading partition {data_day=20190906}
INFO  :         Loading partition {data_day=20190902}
INFO  :         Loading partition {data_day=20190909}
================================中间有一部分略
INFO  :         Loading partition {data_day=20190901}
INFO  :         Loading partition {data_day=20190916}
INFO  :         Loading partition {data_day=20190908}
INFO  :         Loading partition {data_day=20190723}
INFO  :          Time taken for adding to write entity : 12
INFO  : Starting task [Stage-2:STATS] in serial mode
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191001} stats: [numFiles=1, numRows=106817, totalSize=5047510, rawDataSize=4940693]
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191002} stats: [numFiles=1, numRows=142186, totalSize=7349564, rawDataSize=7207378]
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191003} stats: [numFiles=1, numRows=146760, totalSize=7585261, rawDataSize=7438501]
================================中间有一部分略
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191004} stats: [numFiles=1, numRows=115010, totalSize=5880787, rawDataSize=5765777]
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191005} stats: [numFiles=1, numRows=128308, totalSize=6711669, rawDataSize=6583361]
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191006} stats: [numFiles=1, numRows=104644, totalSize=5418150, rawDataSize=5313506]
INFO  : Partition jt_jtsjzxsjyyc_sc_fwfz.app_mbl_user_trmnl_trail_info_d{data_day=20191007} stats: [numFiles=1, numRows=89627, totalSize=4577004, rawDataSize=4487377]
INFO  : MapReduce Jobs Launched: 
INFO  : Stage-Stage-1: Map: 237   Cumulative CPU: 2398.68 sec   HDFS Read: 21622480200 HDFS Write: 459476088 SUCCESS
INFO  : Total MapReduce CPU Time Spent: 39 minutes 58 seconds 680 msec
INFO  : Completed executing command(queryId=hive_2019101011 3232_c82e18e3-5853-43c5-9856-d1d1c55dde45); Time taken: 1008.946 seconds
INFO  : OK
No rows affected (1009.374 seconds)

翻译日志

1. 开始编译 insert 命令，得到一个 queryId
2. 分析 hivesql，语义分析完成
3. 返回 Hive schema：包含 FieldSchema（字段名称，字段类型，字段注释）、properties
4. 编译完成，返回 queryId（与第一步的queryId相同）和编译耗时（以秒为单位）
5. Info：禁用并发模式，不创建锁管理器
6. 执行 insert 命令
7. Info：queryId
8. 3个job
9. 启动job1
10. 在串行模式下启动 task [Stage-1:MAPRED]
11. 因为没有 reduce 算子，所以 reduce 任务的数量被设置为0
12. splits 数量：237
13. 作业令牌标识：job_1569295562481_2677748
14. ...map
15. 作业在 YARN 上的 url 路径：http://host:port/proxy/application_1569295562481_2677748/
16. 开始任务：Job = job_jobName, Tracking URL = http://host:port/proxy/application_1569295562481_2677748/
17. 杀死任务命令：/usr/lib/hadoop/bin/hadoop job  -kill job_jobName
18. Stage-1 Hadoop 作业信息：mapper 数量237，reduce 数量0
19. map 作业进度的百分比......包含（map=X%，reduce=X%，累计CPU xx秒）
20. MapReduce 总累积 CPU 时间：39分58秒680毫秒
21. Info：Job = job_Name
22. 在串行模式下启动task [Stage-7:CONDITIONAL]
23. 阶段4由条件解析器选择。
24. 阶段3被条件分解器过滤掉了。
25. 阶段5被条件分解器过滤掉了。
26. 以串行方式启动任务[阶段4:移动]
27. 将数据从源移动到结果端
28. 在串行模式下启动任务[阶段-0:移动]
29. 将 HDFS 中的数据加载到 Hive 表当中
30. 加载动态分区所需的时间:37085
31. Loading......
32. 添加写入实体所需时间:12
33. 在串行模式下启动task [Stage-2:STATS]
34. Info：分区信息，包含（db.table{data_day=20190620}，stats: [numFiles=1, numRows=222592, totalSize=11316154, rawDataSize=11093562]）
35. MapReduce 任务结束
36. Stage-Stage-1: Map: 237   Cumulative CPU: 2398.68 sec   HDFS Read: 21622480200 HDFS Write: 459476088 SUCCESS
37. 总MapReduce CPU时间花费：39 minutes 58 seconds 680 msec
38. 完成执行命令，实际时间：1008.946 seconds
39. 没有行受影响（总耗时：1009.374 seconds）