Still not clear. What values for mapred.map.tasks and mapred.reduce.tasks do you have now? Check the hadoop-site.xml file as it may affect your configuration also.
Alexander 2008/8/5 brainstorm <[EMAIL PROTECTED]> > 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 > >> > > > -- Best Regards Alexander Aristov
