【Nutch2.2.1基础教程之6】Nutch2.2.1抓取流程

一、抓取流程概述

1、nutch抓取流程

当使用crawl命令进行抓取任务时，其基本流程步骤如下：

（1）InjectorJob

开始第一个迭代

（2）GeneratorJob

（3）FetcherJob

（4）ParserJob

（5）DbUpdaterJob

（6）SolrIndexerJob

开始第二个迭代

（2）GeneratorJob
（3）FetcherJob
（4）ParserJob
（5）DbUpdaterJob
（6）SolrIndexerJob

开始第三个迭代

……

2、抓取日志

使用crawl命令进行抓取时，console输出日志如下：

InjectorJob: starting at 2014-07-08 10:41:27

InjectorJob: Injecting urlDir: urls

InjectorJob: Using class org.apache.gora.hbase.store.HBaseStore as the Gora storage class.

InjectorJob: total number of urls rejected by filters: 0

InjectorJob: total number of urls injected after normalization and filtering: 2

Injector: finished at 2014-07-08 10:41:32, elapsed: 00:00:05

Tue Jul 8 10:41:33 CST 2014 : Iteration 1 of 5

Generating batchId

Generating a new fetchlist

GeneratorJob: starting at 2014-07-08 10:41:34

GeneratorJob: Selecting best-scoring urls due for fetch.

GeneratorJob: starting

GeneratorJob: filtering: false

GeneratorJob: normalizing: false

GeneratorJob: topN: 50000

GeneratorJob: finished at 2014-07-08 10:41:39, time elapsed: 00:00:05

GeneratorJob: generated batch id: 1404787293-26339

Fetching : 

FetcherJob: starting

FetcherJob: batchId: 1404787293-26339

Fetcher: Your 'http.agent.name' value should be listed first in 'http.robots.agents' property.

FetcherJob: threads: 50

FetcherJob: parsing: false

FetcherJob: resuming: false

FetcherJob : timelimit set for : 1404798101129

Using queue mode : byHost

Fetcher: threads: 50

QueueFeeder finished: total 2 records. Hit by time limit :0

fetching http://www.csdn.net/ (queue crawl delay=5000ms)

Fetcher: throughput threshold: -1

Fetcher: throughput threshold sequence: 5

fetching http://www.itpub.net/ (queue crawl delay=5000ms)

-finishing thread FetcherThread47, activeThreads=48

-finishing thread FetcherThread46, activeThreads=47

-finishing thread FetcherThread45, activeThreads=46

-finishing thread FetcherThread44, activeThreads=45

-finishing thread FetcherThread43, activeThreads=44

-finishing thread FetcherThread42, activeThreads=43

-finishing thread FetcherThread41, activeThreads=42

-finishing thread FetcherThread40, activeThreads=41

-finishing thread FetcherThread39, activeThreads=40

-finishing thread FetcherThread38, activeThreads=39

-finishing thread FetcherThread37, activeThreads=38

-finishing thread FetcherThread36, activeThreads=37

-finishing thread FetcherThread35, activeThreads=36

-finishing thread FetcherThread34, activeThreads=35

-finishing thread FetcherThread33, activeThreads=34

-finishing thread FetcherThread32, activeThreads=33

-finishing thread FetcherThread31, activeThreads=32

-finishing thread FetcherThread30, activeThreads=31

-finishing thread FetcherThread29, activeThreads=30

-finishing thread FetcherThread48, activeThreads=29

-finishing thread FetcherThread27, activeThreads=29

-finishing thread FetcherThread26, activeThreads=28

-finishing thread FetcherThread25, activeThreads=27

-finishing thread FetcherThread24, activeThreads=26

-finishing thread FetcherThread23, activeThreads=25

-finishing thread FetcherThread22, activeThreads=24

-finishing thread FetcherThread21, activeThreads=23

-finishing thread FetcherThread20, activeThreads=22

-finishing thread FetcherThread19, activeThreads=21

-finishing thread FetcherThread18, activeThreads=20

-finishing thread FetcherThread17, activeThreads=19

-finishing thread FetcherThread16, activeThreads=18

-finishing thread FetcherThread15, activeThreads=17

-finishing thread FetcherThread14, activeThreads=16

-finishing thread FetcherThread13, activeThreads=15

-finishing thread FetcherThread12, activeThreads=14

-finishing thread FetcherThread11, activeThreads=13

-finishing thread FetcherThread10, activeThreads=12

-finishing thread FetcherThread9, activeThreads=11

-finishing thread FetcherThread8, activeThreads=10

-finishing thread FetcherThread7, activeThreads=9

-finishing thread FetcherThread5, activeThreads=8

-finishing thread FetcherThread4, activeThreads=7

-finishing thread FetcherThread3, activeThreads=6

-finishing thread FetcherThread2, activeThreads=5

-finishing thread FetcherThread49, activeThreads=4

-finishing thread FetcherThread6, activeThreads=3

-finishing thread FetcherThread28, activeThreads=2

-finishing thread FetcherThread0, activeThreads=1

fetch of http://www.itpub.net/ failed with: java.io.IOException: unzipBestEffort returned null

-finishing thread FetcherThread1, activeThreads=0

0/0 spinwaiting/active, 2 pages, 1 errors, 0.4 0 pages/s, 93 93 kb/s, 0 URLs in 0 queues

-activeThreads=0

FetcherJob: done

Parsing : 

ParserJob: starting

ParserJob: resuming:    false

ParserJob: forced reparse:      false

ParserJob: batchId:     1404787293-26339

Parsing http://www.csdn.net/

http://www.csdn.net/ skipped. Content of size 92777 was truncated to 59561

Parsing http://www.itpub.net/

ParserJob: success

CrawlDB update for csdnitpub

DbUpdaterJob: starting

DbUpdaterJob: done

Indexing csdnitpub on SOLR index -> http://ip:8983/solr/

SolrIndexerJob: starting

SolrIndexerJob: done.

SOLR dedup -> http://ip:8983/solr/

Tue Jul 8 10:42:18 CST 2014 : Iteration 2 of 5

Generating batchId

Generating a new fetchlist

GeneratorJob: starting at 2014-07-08 10:42:19

GeneratorJob: Selecting best-scoring urls due for fetch.

GeneratorJob: starting

GeneratorJob: filtering: false

GeneratorJob: normalizing: false

GeneratorJob: topN: 50000

GeneratorJob: finished at 2014-07-08 10:42:25, time elapsed: 00:00:05

GeneratorJob: generated batch id: 1404787338-30453

Fetching : 

FetcherJob: starting

FetcherJob: batchId: 1404787338-30453

Fetcher: Your 'http.agent.name' value should be listed first in 'http.robots.agents' property.

FetcherJob: threads: 50

FetcherJob: parsing: false

FetcherJob: resuming: false

FetcherJob : timelimit set for : 1404798146676

Using queue mode : byHost

Fetcher: threads: 50

QueueFeeder finished: total 0 records. Hit by time limit :0

二、使用命令进行逐步抓取

1、InjectorJob
此步骤将seed.txt中的url注入抓取队列中进行初始化。
（1）基本命令
$ bin/nutch inject 
Usage: InjectorJob <url_dir> [-crawlId <id>]
$ bin/nutch inject urls
InjectorJob: starting at 2014-12-20 22:32:01
InjectorJob: Injecting urlDir: urls
InjectorJob: Using class org.apache.gora.hbase.store.HBaseStore as the Gora storage class.
InjectorJob: total number of urls rejected by filters: 0
InjectorJob: total number of urls injected after normalization and filtering: 1

Injector: finished at 2014-12-20 22:32:15, elapsed: 00:00:14
其中urls/seed.txt的内容如下：
http://stackoverflow.com/

（2）查看注入的url
上述步骤会在hbase中新建一个表，表名为test_1_webpage，url的相应内容会写入这张表
hbase(main):002:0> scan '334_webpage'
ROW                              COLUMN+CELL                                                                               
 com.stackoverflow:http/         column=f:fi, timestamp=1408953100271, value=x00'x8Dx00                                  
 com.stackoverflow:http/         column=f:ts, timestamp=1408953100271, value=x00x00x01Hx0C&x11x8D                     
 com.stackoverflow:http/         column=mk:_injmrk_, timestamp=1408953100271, value=y                                       
 com.stackoverflow:http/         column=mk:dist, timestamp=1408953100271, value=0                                           
 com.stackoverflow:http/         column=mtdt:_csh_, timestamp=1408953100271, value=?x80x00x00                            
 com.stackoverflow:http/         column=s:s, timestamp=1408953100271, value=?x80x00x00                                   
1 row(s) in 0.3020 seconds

(3)关于**_webpage表
对于每一个任务，均会生成一个crawlId_webpage的表，所有已抓取及未抓取的url相关信息均会存入此表。
若url未抓取，则该url相应的行信息较少。若url已经抓取，则抓取到的内容也会放入该行，如网页内容等。


2、GeneratorJob
（1）基本命令
[jediael@jediael local]$  bin/nutch generate -crawlId 334
GeneratorJob: starting at 2014-08-25 15:57:12
GeneratorJob: Selecting best-scoring urls due for fetch.
GeneratorJob: starting
GeneratorJob: filtering: true
GeneratorJob: normalizing: true
GeneratorJob: finished at 2014-08-25 15:57:18, time elapsed: 00:00:06
GeneratorJob: generated batch id: 1408953432-1171377744

（2）命令选项
[root@jediael local]# bin/nutch generate
Usage: GeneratorJob [-topN N] [-crawlId id] [-noFilter] [-noNorm] [-adddays numDays]
 -topN <N>      - number of top URLs to be selected, default is Long.MAX_VALUE 
   -crawlId <id>  - the id to prefix the schemas to operate on, default: storage.crawl.id)"); 
   -noFilter      - do not activate the filter plugin to filter the url, default is true 
    -noNorm        - do not activate the normalizer plugin to normalize the url, default is true 
    -adddays       - Adds numDays to the current time to facilitate crawling urls already fetched sooner then db.fetch.interval.default. Default value is 0.
    -batchId       - the batch id 
----------------------
Please set the params.

（3）查看数据库
hbase(main):003:0> scan '334_webpage' 
ROW                              COLUMN+CELL                                                                                
 com.stackoverflow:http/         column=f:bid, timestamp=1408953437910, value=1408953432-1171377744                         
 com.stackoverflow:http/         column=f:fi, timestamp=1408953100271, value=x00'x8Dx00                                  
 com.stackoverflow:http/         column=f:ts, timestamp=1408953100271, value=x00x00x01Hx0C&x11x8D                     
 com.stackoverflow:http/         column=mk:_gnmrk_, timestamp=1408953437910, value=1408953432-1171377744                    
 com.stackoverflow:http/         column=mk:_injmrk_, timestamp=1408953100271, value=y                                       
 com.stackoverflow:http/         column=mk:dist, timestamp=1408953100271, value=0                                           
 com.stackoverflow:http/         column=mtdt:_csh_, timestamp=1408953100271, value=?x80x00x00                            
 com.stackoverflow:http/         column=s:s, timestamp=1408953100271, value=?x80x00x00                                   
1 row(s) in 0.0490 seconds
此步骤新增了f:bid，mk:_gnmrk_  两列。

3、FetcherJob
（1）基本命令
[jediael@jediael local]$  bin/nutch generate -crawlId 334
GeneratorJob: starting at 2014-08-25 15:57:12
GeneratorJob: Selecting best-scoring urls due for fetch.
GeneratorJob: starting
GeneratorJob: filtering: true
GeneratorJob: normalizing: true
GeneratorJob: finished at 2014-08-25 15:57:18, time elapsed: 00:00:06
GeneratorJob: generated batch id: 1408953432-1171377744
[jediael@jediael local]$  bin/nutch fetch -all -crawlId 334
FetcherJob: starting
FetcherJob: fetching all
Fetcher: Your 'http.agent.name' value should be listed first in 'http.robots.agents' property.
FetcherJob: threads: 10
FetcherJob: parsing: false
FetcherJob: resuming: false
FetcherJob : timelimit set for : -1
Using queue mode : byHost
Fetcher: threads: 10
QueueFeeder finished: total 1 records. Hit by time limit :0
Fetcher: throughput threshold: -1
Fetcher: throughput threshold sequence: 5
fetching http://stackoverflow.com/ (queue crawl delay=5000ms)
-finishing thread FetcherThread1, activeThreads=8
-finishing thread FetcherThread7, activeThreads=7
-finishing thread FetcherThread6, activeThreads=6
-finishing thread FetcherThread5, activeThreads=5
-finishing thread FetcherThread4, activeThreads=4
-finishing thread FetcherThread3, activeThreads=3
-finishing thread FetcherThread2, activeThreads=2
-finishing thread FetcherThread8, activeThreads=1
-finishing thread FetcherThread9, activeThreads=1
-finishing thread FetcherThread0, activeThreads=0
0/0 spinwaiting/active, 1 pages, 0 errors, 0.2 0 pages/s, 102 102 kb/s, 0 URLs in 0 queues
-activeThreads=0
FetcherJob: done

（2）查看数据库
见db1.txt
新增f:bas，column=f:cnt，column=f:prot，f:pts，f:st，f:ts，f:typ，h:Cache-Control，h:Connection，h:Content-Encoding，h:Content-Length, h:Content-Type,h:Date,h:Expires, h:Last-Modified,h:Set-Cookie,h:Vary,h:X-Frame-Options, mk:_ftcmrk_等字段

4、ParserJob
（1）基本命令
[jediael@jediael local]$ bin/nutch parse  -all -crawlId 334
ParserJob: starting
ParserJob: resuming:    false
ParserJob: forced reparse:      false
ParserJob: parsing all
Parsing http://stackoverflow.com/
ParserJob: success

（2）命令参数
[root@jediael local]# bin/nutch parse 
Usage: ParserJob (<batchId> | -all) [-crawlId <id>] [-resume] [-force]
    <batchId>     - symbolic batch ID created by Generator
    -crawlId <id> - the id to prefix the schemas to operate on, 

                    (default: storage.crawl.id)
    -all          - consider pages from all crawl jobs
    -resume       - resume a previous incomplete job
    -force        - force re-parsing even if a page is already parsed

（3）查看数据库
见db_parse.txt
新增了很多类似column=ol:http://stackoverflow.com/help的列，在此例中共有115个。


5、DbUpdaterJob
（1）基本命令
[jediael@jediael local]$ bin/nutch updatedb -crawlId 334
DbUpdaterJob: starting
DbUpdaterJob: done

（2）查看数据库
见db_updatedb.txt
解释了上述的115个column=ol:http，并生成了115行新数据，举其中一个例子如下：
com.stackoverflow:http/users/39 column=f:fi, timestamp=1408954979355, value=x00'x8Dx00                                  
 44974/silviu-oncioiu                                                                                                       
 com.stackoverflow:http/users/39 column=f:st, timestamp=1408954979355, value=x00x00x00x01                               
 44974/silviu-oncioiu                                                                                                       
 com.stackoverflow:http/users/39 column=f:ts, timestamp=1408954979355, value=x00x00x01Hx0CBxD4x09                     
 44974/silviu-oncioiu                                                                                                       
 com.stackoverflow:http/users/39 column=mk:dist, timestamp=1408954979355, value=1                                           
 44974/silviu-oncioiu                                                                                                       
 com.stackoverflow:http/users/39 column=mtdt:_csh_, timestamp=1408954979355, value=<x0Ex5                                  
 44974/silviu-oncioiu                                                                                                       
 com.stackoverflow:http/users/39 column=s:s, timestamp=1408954979355, value=<x0Ex5                                         
 44974/silviu-oncioiu                                                                                                       
 com.stackoverflow:http/users/39 column=f:fi, timestamp=1408954979355, value=x00'x8Dx00                                  
 74525/laosi                                                                                                                
 com.stackoverflow:http/users/39 column=f:st, timestamp=1408954979355, value=x00x00x00x01                               
 74525/laosi                                                                                                                
 com.stackoverflow:http/users/39 column=f:ts, timestamp=1408954979355, value=x00x00x01Hx0CBxD4x09                     
 74525/laosi                                                                                                                
 com.stackoverflow:http/users/39 column=mk:dist, timestamp=1408954979355, value=1                                           
 74525/laosi                                                                                                                
 com.stackoverflow:http/users/39 column=mtdt:_csh_, timestamp=1408954979355, value=<x0Ex5                                  
 74525/laosi                                                                                                                
 com.stackoverflow:http/users/39 column=s:s, timestamp=1408954979355, value=<x0Ex5                                         
 74525/laosi 
此时数据已准备好，等待下一轮的抓取。

6、SolrIndexerJob
（1）基本命令
[jediael@jediael local]$  bin/nutch solrindex http://****/solr/  -all -crawlId 334
SolrIndexerJob: starting
Adding 1 documents
SolrIndexerJob: done.

（2）命令参数
[root@jediael local]# bin/nutch solrindex 
Usage: SolrIndexerJob <solr url> (<batchId> | -all | -reindex) [-crawlId <id>]

（3）查看数据库
无变化