Correction: Only 2 nodes doing map operation on fetch (nodes 7 and 2).
On Tue, Aug 5, 2008 at 9:11 AM, brainstorm <[EMAIL PROTECTED]> wrote: > Right, I've checked before with mapred.map.tasks to 2 and > mapred.reduce.tasks to 1. > > I've also played with several values on the following settings: > > <property> > <name>fetcher.server.delay</name> > <value>1.5</value> > <description>The number of seconds the fetcher will delay between > successive requests to the same server.</description> > </property> > > <property> > <name>http.max.delays</name> > <value>3</value> > <description>The number of times a thread will delay when trying to > fetch a page. Each time it finds that a host is busy, it will wait > fetcher.server.delay. After http.max.delays attepts, it will give > up on the page for now.</description> > </property> > > Only one node executes the fetch phase anyway :_( > > Thanks for the hint anyway... more ideas ? > > On Tue, Aug 5, 2008 at 8:04 AM, Alexander Aristov > <[EMAIL PROTECTED]> wrote: >> Hi >> >> 1. You should have set >> mapred.map.tasks >> and >> mapred.reduce.tasks parameters They are set to 2 and 1 by default. >> >> 2. You can specify number of threads to perform fetching. Also there is a >> parameter that slows down fetching from one URL,so called polite fetching to >> not DOS the site. >> >> So check you configuration. >> >> Alex >> >> 2008/8/5 brainstorm <[EMAIL PROTECTED]> >> >>> Ok, DFS warnings problem solved, seems that hadoop-0.17.1 patch fixes >>> the warnings... BUT, on a 7-node nutch cluster: >>> >>> 1) Fetching is only happening on *one* node despite several values >>> tested on settings: >>> mapred.tasktracker.map.tasks.maximum >>> mapred.tasktracker.reduce.tasks.maximum >>> export HADOOP_HEAPSIZE >>> >>> I've played with mapreduce (hadoop-site.xml) settings as advised on: >>> >>> http://wiki.apache.org/hadoop/HowManyMapsAndReduces >>> >>> But nutch keeps crawling only using one node, instead of seven >>> nodes... anybody knows why ? >>> >>> I've had a look at the code, searching for: >>> >>> conf.setNumMapTasks(int num), but found none: so I guess that the >>> number of mappers & reducers are not limited programatically. >>> >>> 2) Even on a single node, the fetching is really slow: 1 url or page >>> per second, at most. >>> >>> Can anybody shed some light into this ? Pointing which class/code I >>> should look into to modify this behaviour will help also. >>> >>> Anybody has a distributed nutch crawling cluster working with all >>> nodes fetching at fetch phase ? >>> >>> I even did some numbers using wordcount example using 7 nodes at 100% >>> cpu usage using a 425MB parsedtext file: >>> >>> maps reduces heapsize time >>> 2 2 500 3m43.049s >>> 4 4 500 4m41.846s >>> 8 8 500 4m29.344s >>> 16 16 500 3m43.672s >>> 32 32 500 3m41.367s >>> 64 64 500 4m27.275s >>> 128 128 500 4m35.233s >>> 256 256 500 3m41.916s >>> >>> >>> 2 2 2000 4m31.434s >>> 4 4 2000 >>> 8 8 2000 >>> 16 16 2000 4m32.213s >>> 32 32 2000 >>> 64 64 2000 >>> 128 128 2000 >>> 256 256 2000 4m38.310s >>> >>> Thanks in advance, >>> Roman >>> >>> On Tue, Jul 15, 2008 at 7:15 PM, brainstorm <[EMAIL PROTECTED]> wrote: >>> > While seeing DFS wireshark trace (and the corresponding RST's), the >>> > crawl continued to next step... seems that this WARNING is actually >>> > slowing down the whole crawling process (it took 36 minutes to >>> > complete the previous fetch) with just 3 urls seed file :-!!! >>> > >>> > I just posted a couple of exceptions/questions regarding DFS on hadoop >>> > core mailing list. >>> > >>> > PD: As a side note, the following error caught my attention: >>> > >>> > Fetcher: starting >>> > Fetcher: segment: crawl-ecxi/segments/20080715172458 >>> > Too many fetch-failures >>> > task_200807151723_0005_m_000000_0: Fetcher: threads: 10 >>> > task_200807151723_0005_m_000000_0: fetching http://upc.es/ >>> > task_200807151723_0005_m_000000_0: fetching http://upc.edu/ >>> > task_200807151723_0005_m_000000_0: fetching http://upc.cat/ >>> > task_200807151723_0005_m_000000_0: fetch of http://upc.cat/ failed >>> > with: org.apache.nutch.protocol.http.api.HttpException: >>> > java.net.UnknownHostException: upc.cat >>> > >>> > Unknown host ?¿ Just try "http://upc.cat"; on your browser, it *does* >>> > exist, it just gets redirected to www.upc.cat :-/ >>> > >>> > On Tue, Jul 15, 2008 at 5:42 PM, brainstorm <[EMAIL PROTECTED]> wrote: >>> >> Yep, I know about wireshark, and wanted to avoid it to debug this >>> >> issue (perhaps there was a simple solution/known bug/issue)... >>> >> >>> >> I just launched wireshark on frontend with filter tcp.port == 50010, >>> >> and now I'm diving on the tcp stream... let's see if I see the light >>> >> (RST flag somewhere ?), thanks anyway for replying ;) >>> >> >>> >> Just for the record, the phase that stalls is fetcher during reduce: >>> >> >>> >> Jobid User Name Map % Complete Map Total Maps Completed >>> Reduce % >>> >> Complete Reduce Total Reduces Completed >>> >> job_200807151723_0005 hadoop fetch crawl-ecxi/segments/20080715172458 >>> 100.00% >>> >> 2 2 16.66% >>> >> >>> >> 1 0 >>> >> >>> >> It's stuck on 16%, no traffic, no crawling, but still "running". >>> >> >>> >> On Tue, Jul 15, 2008 at 4:28 PM, Patrick Markiewicz >>> >> <[EMAIL PROTECTED]> wrote: >>> >>> Hi brain, >>> >>> If I were you, I would download wireshark >>> >>> (http://www.wireshark.org/download.html) to see what is happening at >>> the >>> >>> network layer and see if that provides any clues. A socket exception >>> >>> that you don't expect is usually due to one side of the conversation >>> not >>> >>> understanding the other side. If you have 4 machines, then you have 4 >>> >>> possible places where default firewall rules could be causing an issue. >>> >>> If it is not the firewall rules, the NAT rules could be a potential >>> >>> source of error. Also, even a router hardware error could cause a >>> >>> problem. >>> >>> If you understand TCP, just make sure that you see all the >>> >>> correct TCP stuff happening in wireshark. If you don't understand >>> >>> wireshark's display, let me know, and I'll pass on some quickstart >>> >>> information. >>> >>> >>> >>> If you already know all of this, I don't have any way to help >>> >>> you, as it looks like you're trying to accomplish something trickier >>> >>> with nutch than I have ever attempted. >>> >>> >>> >>> Patrick >>> >>> >>> >>> -----Original Message----- >>> >>> From: brainstorm [mailto:[EMAIL PROTECTED] >>> >>> Sent: Tuesday, July 15, 2008 10:08 AM >>> >>> To: [email protected] >>> >>> Subject: Re: Distributed fetching only happening in one node ? >>> >>> >>> >>> Boiling down the problem I'm stuck on this: >>> >>> >>> >>> 2008-07-14 16:43:24,976 WARN dfs.DataNode - >>> >>> 192.168.0.100:50010:Failed to transfer blk_-855404545666908011 to >>> >>> 192.168.0.252:50010 got java.net.SocketException: Connection reset >>> >>> at >>> >>> java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:96) >>> >>> at >>> >>> java.net.SocketOutputStream.write(SocketOutputStream.java:136) >>> >>> at >>> >>> java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) >>> >>> at >>> >>> java.io.BufferedOutputStream.write(BufferedOutputStream.java:109) >>> >>> at java.io.DataOutputStream.write(DataOutputStream.java:90) >>> >>> at >>> >>> >>> org.apache.hadoop.dfs.DataNode$BlockSender.sendChunk(DataNode.java:1602) >>> >>> at >>> >>> >>> org.apache.hadoop.dfs.DataNode$BlockSender.sendBlock(DataNode.java:1636) >>> >>> at >>> >>> org.apache.hadoop.dfs.DataNode$DataTransfer.run(DataNode.java:2391) >>> >>> at java.lang.Thread.run(Thread.java:595) >>> >>> >>> >>> Checked that firewall settings between node & frontend were not >>> >>> blocking packets, and they don't... anyone knows why is this ? If not, >>> >>> could you provide a convenient way to debug it ? >>> >>> >>> >>> Thanks ! >>> >>> >>> >>> On Sun, Jul 13, 2008 at 3:41 PM, brainstorm <[EMAIL PROTECTED]> >>> wrote: >>> >>>> Hi, >>> >>>> >>> >>>> I'm running nutch+hadoop from trunk (rev) on a 4 machine rocks >>> >>>> cluster: 1 frontend doing NAT to 3 leaf nodes. I know it's not the >>> >>>> best suited network topology for inet crawling (frontend being a net >>> >>>> bottleneck), but I think it's fine for testing purposes. >>> >>>> >>> >>>> I'm having issues with fetch mapreduce job: >>> >>>> >>> >>>> According to ganglia monitoring (network traffic), and hadoop >>> >>>> administrative interfaces, fetch phase is only being executed in the >>> >>>> frontend node, where I launched "nutch crawl". Previous nutch phases >>> >>>> were executed neatly distributed on all nodes: >>> >>>> >>> >>>> job_200807131223_0001 hadoop inject urls 100.00% >>> >>>> 2 2 100.00% >>> >>>> 1 1 >>> >>>> job_200807131223_0002 hadoop crawldb crawl-ecxi/crawldb >>> >>> 100.00% >>> >>>> 3 3 100.00% >>> >>>> 1 1 >>> >>>> job_200807131223_0003 hadoop generate: select >>> >>>> crawl-ecxi/segments/20080713123547 100.00% >>> >>>> 3 3 100.00% >>> >>>> 1 1 >>> >>>> job_200807131223_0004 hadoop generate: partition >>> >>>> crawl-ecxi/segments/20080713123547 100.00% >>> >>>> 4 4 100.00% >>> >>>> 2 2 >>> >>>> >>> >>>> I've checked that: >>> >>>> >>> >>>> 1) Nodes have inet connectivity, firewall settings >>> >>>> 2) There's enough space on local discs >>> >>>> 3) Proper processes are running on nodes >>> >>>> >>> >>>> frontend-node: >>> >>>> ========== >>> >>>> >>> >>>> [EMAIL PROTECTED] ~]# jps >>> >>>> 29232 NameNode >>> >>>> 29489 DataNode >>> >>>> 29860 JobTracker >>> >>>> 29778 SecondaryNameNode >>> >>>> 31122 Crawl >>> >>>> 30137 TaskTracker >>> >>>> 10989 Jps >>> >>>> 1818 TaskTracker$Child >>> >>>> >>> >>>> leaf nodes: >>> >>>> ======== >>> >>>> >>> >>>> [EMAIL PROTECTED] ~]# cluster-fork jps >>> >>>> compute-0-1: >>> >>>> 23929 Jps >>> >>>> 15568 TaskTracker >>> >>>> 15361 DataNode >>> >>>> compute-0-2: >>> >>>> 32272 TaskTracker >>> >>>> 32065 DataNode >>> >>>> 7197 Jps >>> >>>> 2397 TaskTracker$Child >>> >>>> compute-0-3: >>> >>>> 12054 DataNode >>> >>>> 19584 Jps >>> >>>> 14824 TaskTracker$Child >>> >>>> 12261 TaskTracker >>> >>>> >>> >>>> 4) Logs only show fetching process (taking place only in the head >>> >>> node): >>> >>>> >>> >>>> 2008-07-13 13:33:22,306 INFO fetcher.Fetcher - fetching >>> >>>> http://valleycycles.net/ >>> >>>> 2008-07-13 13:33:22,349 INFO api.RobotRulesParser - Couldn't get >>> >>>> robots.txt for http://www.getting-forward.org/: >>> >>>> java.net.UnknownHostException: www.getting-forward.org >>> >>>> 2008-07-13 13:33:22,349 INFO api.RobotRulesParser - Couldn't get >>> >>>> robots.txt for http://www.getting-forward.org/: >>> >>>> java.net.UnknownHostException: www.getting-forward.org >>> >>>> >>> >>>> What am I missing ? Why there are no fetching instances on nodes ? I >>> >>>> used the following custom script to launch a pristine crawl each time: >>> >>>> >>> >>>> #!/bin/sh >>> >>>> >>> >>>> # 1) Stops hadoop daemons >>> >>>> # 2) Overwrites new url list on HDFS >>> >>>> # 3) Starts hadoop daemons >>> >>>> # 4) Performs a clean crawl >>> >>>> >>> >>>> #export JAVA_HOME=/usr/lib/jvm/java-6-sun >>> >>>> export JAVA_HOME=/usr/java/jdk1.5.0_10 >>> >>>> >>> >>>> CRAWL_DIR=crawl-ecxi || $1 >>> >>>> URL_DIR=urls || $2 >>> >>>> >>> >>>> echo $CRAWL_DIR >>> >>>> echo $URL_DIR >>> >>>> >>> >>>> echo "Leaving safe mode..." >>> >>>> ./hadoop dfsadmin -safemode leave >>> >>>> >>> >>>> echo "Removing seed urls directory and previous crawled content..." >>> >>>> ./hadoop dfs -rmr $URL_DIR >>> >>>> ./hadoop dfs -rmr $CRAWL_DIR >>> >>>> >>> >>>> echo "Removing past logs" >>> >>>> >>> >>>> rm -rf ../logs/* >>> >>>> >>> >>>> echo "Uploading seed urls..." >>> >>>> ./hadoop dfs -put ../$URL_DIR $URL_DIR >>> >>>> >>> >>>> #echo "Entering safe mode..." >>> >>>> #./hadoop dfsadmin -safemode enter >>> >>>> >>> >>>> echo "******************" >>> >>>> echo "* STARTING CRAWL *" >>> >>>> echo "******************" >>> >>>> >>> >>>> ./nutch crawl $URL_DIR -dir $CRAWL_DIR -depth 3 >>> >>>> >>> >>>> >>> >>>> Next step I'm thinking on to fix the problem is to install >>> >>>> nutch+hadoop as specified in this past nutch-user mail: >>> >>>> >>> >>>> >>> http://www.mail-archive.com/[email protected]/msg10225.html >>> >>>> >>> >>>> As I don't know if it's current practice on trunk (archived mail is >>> >>>> from Wed, 02 Jan 2008), I wanted to ask if there's another way to fix >>> >>>> it or if it's being worked on by someone... I haven't found a matching >>> >>>> bug on JIRA :_/ >>> >>>> >>> >>> >>> >> >>> > >>> >> >> >> >> -- >> Best Regards >> Alexander Aristov >> >
