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 >
